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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"><html lang="en-US"><head>
  <title>XMLHttpRequest Level 2</title>
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   <h1 class="head" id="xmlhttprequest-level-2">XMLHttpRequest Level 2</h1>

   <h2 class="no-num no-toc" id="w3c-doctype">W3C Working Draft 16 August 2011</h2>

   <dl>
    <dt>This Version:</dt>
    <dd class="publish"><a href="http://www.w3.org/TR/2011/WD-XMLHttpRequest2-20110816/">http://www.w3.org/TR/2011/WD-XMLHttpRequest2-20110816/</a></dd>

    <dt class="publish">Latest Version:</dt>
    <dd class="publish"><a href="http://www.w3.org/TR/XMLHttpRequest2/">http://www.w3.org/TR/XMLHttpRequest2/</a></dd>

    <dt class="publish">Latest Editor's Draft:</dt>
    <dd class="publish"><a href="http://dev.w3.org/2006/webapi/XMLHttpRequest-2/">http://dev.w3.org/2006/webapi/XMLHttpRequest-2/</a></dd>

    <dt>Previous Versions:</dt>


    <dd><a href="http://www.w3.org/TR/2010/WD-XMLHttpRequest2-20100907/">http://www.w3.org/TR/2010/WD-XMLHttpRequest2-20100907/</a></dd>
    <dd><a href="http://www.w3.org/TR/2009/WD-XMLHttpRequest2-20090820/">http://www.w3.org/TR/2009/WD-XMLHttpRequest2-20090820/</a></dd>
    <dd><a href="http://www.w3.org/TR/2008/WD-XMLHttpRequest2-20080930/">http://www.w3.org/TR/2008/WD-XMLHttpRequest2-20080930/</a></dd>
    <dd><a href="http://www.w3.org/TR/2008/WD-XMLHttpRequest2-20080225/">http://www.w3.org/TR/2008/WD-XMLHttpRequest2-20080225/</a></dd>


    <dt>Editor:</dt>
    <dd><a href="http://annevankesteren.nl/">Anne van Kesteren</a>
     (<a href="http://www.opera.com/">Opera Software ASA</a>)
     &lt;<a href="mailto:annevk@opera.com">annevk@opera.com</a>&gt;</dd>
   </dl>


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<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> &copy; 2011 <a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>&reg;</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p>
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  </div>

  <hr>

  <h2 class="no-num no-toc" id="specabstract">Abstract</h2>


  <p>The XMLHttpRequest Level 2 specification enhances the
  <code title="">XMLHttpRequest</code> object with new features, such as
  cross-origin requests, progress events, and the handling of byte streams
  for both sending and receiving.</p>



  <h2 class="no-num no-toc" id="sotd">Status of this Document</h2>

  <p><em>This section describes the status of this document at the time of its
  publication. Other documents may supersede this document. A list of current
  W3C publications and the latest revision of this technical report can be
  found in the <a href="http://www.w3.org/TR/">W3C technical reports index</a>
  at http://www.w3.org/TR/.</em></p>

  <p>This is the 16 August 2011 W3C Working Draft of
  XMLHttpRequest Level 2. Please send comments to
  <a href="mailto:public-webapps@w3.org?subject=[XHR2]%20">public-webapps@w3.org</a>
  (<a href="http://lists.w3.org/Archives/Public/public-webapps/">archived</a>)
  with <samp>[XHR2]</samp> at the start of the subject line.</p>



  <p>This document is produced by the
  <a href="http://www.w3.org/2008/webapps/">Web Applications</a> (WebApps) Working Group.
  The WebApps Working Group is part of the
  <a href="http://www.w3.org/2006/rwc/Activity">Rich Web Clients Activity</a>
  in the W3C <a href="http://www.w3.org/Interaction/">Interaction Domain</a>.</p>

  <p>This document was produced by a group operating under the
  <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February 2004
  W3C Patent Policy</a>. W3C maintains a
  <a href="http://www.w3.org/2004/01/pp-impl/42538/status" rel="disclosure">public
  list of any patent disclosures</a> made in connection with the deliverables of
  the group; that page also includes instructions for disclosing a patent. An
  individual who has actual knowledge of a patent which the individual believes
  contains
  <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
  Claim(s)</a> must disclose the information in accordance with
  <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
  6 of the W3C Patent Policy</a>.</p>

  <p>Publication as a Working Draft does not imply endorsement by the W3C
  Membership. This is a draft document and may be updated, replaced or
  obsoleted by other documents at any time. It is inappropriate to cite this
  document as other than work in progress.</p>




  <h2 class="no-num no-toc" id="toc">Table of Contents</h2>


<!--begin-toc-->
<ol class="toc">
 <li><a href="#introduction"><span class="secno">1 </span>Introduction</a></li>
 <li><a href="#conformance"><span class="secno">2 </span>Conformance</a>
  <ol class="toc">
   <li><a href="#dependencies"><span class="secno">2.1 </span>Dependencies</a></li>
   <li><a href="#extensibility"><span class="secno">2.2 </span>Extensibility</a></ol></li>
 <li><a href="#terminology"><span class="secno">3 </span>Terminology</a></li>
 <li><a href="#the-xmlhttprequest-interface"><span class="secno">4 </span>The <code title="">XMLHttpRequest</code> Interface</a>
  <ol class="toc">
   <li><a href="#origin-and-base-url"><span class="secno">4.1 </span>Origin and Base URL</a></li>
   <li><a href="#task-sources"><span class="secno">4.2 </span>Task Sources</a></li>
   <li><a href="#constructors"><span class="secno">4.3 </span>Constructors</a></li>
   <li><a href="#event-handlers"><span class="secno">4.4 </span>Event Handlers</a></li>
   <li><a href="#states"><span class="secno">4.5 </span>States</a></li>
   <li><a href="#request"><span class="secno">4.6 </span>Request</a>
    <ol class="toc">
     <li><a href="#the-open-method"><span class="secno">4.6.1 </span>The <code title="">open()</code> method</a></li>
     <li><a href="#the-setrequestheader-method"><span class="secno">4.6.2 </span>The <code title="">setRequestHeader()</code> method</a></li>
     <li><a href="#the-timeout-attribute"><span class="secno">4.6.3 </span>The <code title="">timeout</code> attribute</a></li>
     <li><a href="#the-withcredentials-attribute"><span class="secno">4.6.4 </span>The <code title="">withCredentials</code> attribute</a></li>
     <li><a href="#the-upload-attribute"><span class="secno">4.6.5 </span>The <code title="">upload</code> attribute</a></li>
     <li><a href="#the-send-method"><span class="secno">4.6.6 </span>The <code title="">send()</code> method</a></li>
     <li><a href="#infrastructure-for-the-send-method"><span class="secno">4.6.7 </span>Infrastructure for the <code title="">send()</code> method</a></li>
     <li><a href="#the-abort-method"><span class="secno">4.6.8 </span>The <code title="">abort()</code> method</a></ol></li>
   <li><a href="#response"><span class="secno">4.7 </span>Response</a>
    <ol class="toc">
     <li><a href="#the-status-attribute"><span class="secno">4.7.1 </span>The <code title="">status</code> attribute</a></li>
     <li><a href="#the-statustext-attribute"><span class="secno">4.7.2 </span>The <code title="">statusText</code> attribute</a></li>
     <li><a href="#the-getresponseheader-method"><span class="secno">4.7.3 </span>The <code title="">getResponseHeader()</code> method</a></li>
     <li><a href="#the-getallresponseheaders-method"><span class="secno">4.7.4 </span>The <code title="">getAllResponseHeaders()</code> method</a></li>
     <li><a href="#response-entity-body-0"><span class="secno">4.7.5 </span>Response Entity Body</a></li>
     <li><a href="#the-overridemimetype-method"><span class="secno">4.7.6 </span>The <code title="">overrideMimeType()</code> method</a></li>
     <li><a href="#the-responsetype-attribute"><span class="secno">4.7.7 </span>The <code title="">responseType</code> attribute</a></li>
     <li><a href="#the-response-attribute"><span class="secno">4.7.8 </span>The <code title="">response</code> attribute</a></li>
     <li><a href="#the-responsetext-attribute"><span class="secno">4.7.9 </span>The <code title="">responseText</code> attribute</a></li>
     <li><a href="#the-responsexml-attribute"><span class="secno">4.7.10 </span>The <code title="">responseXML</code> attribute</a></ol></li>
   <li><a href="#events"><span class="secno">4.8 </span>Events summary</a></ol></li>
 <li><a href="#the-formdata-interface"><span class="secno">5 </span>The <code title="">FormData</code> Interface</a>
  <ol class="toc">
   <li><a href="#formdata-constructors"><span class="secno">5.1 </span>Constructors</a></li>
   <li><a href="#the-append-method"><span class="secno">5.2 </span>The <code title="">append()</code> method</a></ol></li>
 <li><a class="no-num" href="#differences">Differences from XMLHttpRequest</a></li>
 <li><a class="no-num" href="#references">References</a>
  <ol class="toc">
   <li><a class="no-num" href="#normative-references">Normative references</a></li>
   <li><a class="no-num" href="#informative-references">Informative references</a></ol></li>
 <li><a class="no-num" href="#acknowledgments">Acknowledgments</a></ol>
<!--end-toc-->



  <h2 id="introduction"><span class="secno">1 </span>Introduction</h2>

  <p><em>This section is non-normative.</em></p>

  <p>The <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object implements an interface exposed
  by a scripting engine that allows scripts to perform HTTP client
  functionality, such as submitting form data or loading data from a
  server. It is the ECMAScript HTTP API.
  <a class="informative" href="#refsECMASCRIPT">[ECMASCRIPT]</a>

  <p>The name of the object is <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> for compatibility
  with the Web, though each component of this name is potentially
  misleading. First, the object supports any text based format, including
  XML. Second, it can be used to make requests over both HTTP and HTTPS
  (some implementations support protocols in addition to HTTP and HTTPS, but
  that functionality is not covered by this specification). Finally, it
  supports "requests" in a broad sense of the term as it pertains to HTTP;
  namely all activity involved with HTTP requests or responses for the
  defined HTTP methods.</p>

  <div class="example">
   <p>Some simple code to do something with data from an XML document
   fetched over the network:</p>

   <pre><code>function processData(data) {
  // taking care of data
}

function handler() {
  if(this.readyState == this.DONE) {
    if(this.status == 200 &amp;&amp;
       this.responseXML != null &amp;&amp;
       this.responseXML.getElementById('test').textContent) {
      // success!
      processData(this.responseXML.getElementById('test').textContent);
      return;
    }
    // something went wrong
    processData(null);
  }
}

var client = new XMLHttpRequest();
client.onreadystatechange = handler;
client.open("GET", "unicorn.xml");
client.send();</code></pre>

   <p>If you just want to log a message to the server:</p>

   <pre><code>function log(message) {
  var client = new XMLHttpRequest();
  client.open("POST", "/log");
  client.setRequestHeader("Content-Type", "text/plain;charset=UTF-8");
  client.send(message);
}</code></pre>

   <p>Or if you want to check the status of a document on the server:</p>

   <pre><code>function fetchStatus(address) {
  var client = new XMLHttpRequest();
  client.onreadystatechange = function() {
    // in case of network errors this might not give reliable results
    if(this.readyState == this.DONE)
      returnStatus(this.status);
  }
  client.open("HEAD", address);
  client.send();
}</code></pre>
  </div>




  <h2 id="conformance"><span class="secno">2 </span>Conformance</h2>

  <p>Everything in this specification is normative except for diagrams,
  examples, notes and sections marked non-normative.</p>

  <p>The key words must, must not, should, should not and may in this
  document are to be interpreted as described in RFC 2119.
  <a href="#refsRFC2119">[RFC2119]</a></p>

  <p>This specification defines a single conformance class:</p>

  <dl>
   <dt><dfn id="conforming-user-agent">Conforming user agent</dfn></dt>

   <dd>
    <p>A user agent must behave as described in this
    specification in order to be considered conformant.</p>

    <p>User agents may implement algorithms given in
    this specification in any way desired, so long as the end result is
    indistinguishable from the result that would be obtained by the
    specification's algorithms.</p>

    <p class="note">This specification uses both the terms "conforming user
    agent(s)" and "user agent(s)" to refer to this product class.</p>
   </dd>
  </dl>

  <h3 id="dependencies"><span class="secno">2.1 </span>Dependencies</h3>

  <p>This specification relies on several underlying specifications.</p>

  <dl>

   <dt>Cross-Origin Resource Sharing</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must
   support the algorithms of the Cross-Origin Resource Sharing
   specification. <a href="#refsCORS">[CORS]</a></dd>


   <dt>DOM Core</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must
   support at least the subset of the functionality defined in DOM Core that
   this specification relies upon, such as various exceptions and
   <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#eventtarget">EventTarget</a></code>. <a href="#refsDOMCORE">[DOMCORE]</a></dd>

   <dt>File API</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must
   support at least the subset of the functionality defined in File API that
   this specification relies upon, such as the <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a></code> and
   <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#file">File</a></code> interfaces. <a href="#refsFILEAPI">[FILEAPI]</a></p>


   <dt>HTML</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must
   support at least the subset of the functionality defined in HTML that
   this specification relies upon, such as the basics of the
   <code class="external"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#window">Window</a></code> object and serializing a <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code>
   object. <a href="#refsHTML">[HTML]</a>

   <dt>HTTP</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must
   support some version of the HTTP protocol. Requirements regarding HTTP
   are made throughout the specification. <a href="#refsHTTP">[HTTP]</a>


   <dt>Progress Events</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must support the
   Progress Events specification.
   <a href="#refsPROGRESSEVENTS">[PROGRESSEVENTS]</a>

   <dt>Typed Array</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must support the
   <code class="external"><a href="http://www.khronos.org/registry/typedarray/specs/latest/#5">ArrayBuffer</a></code> object.
   <a href="#refsTYPEDARRAY">[TYPEDARRAY]</a>


   <dt>Web IDL</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must also
   be a conforming implementation of the IDL fragments in this
   specification, as described in the Web IDL specification.
   <a href="#refsWEBIDL">[WEBIDL]</a>

   <dt>XML</dt>
   <dd><p>A <a href="#conforming-user-agent">conforming user agent</a> must be a
   conforming XML processor that reports violations of namespace
   well-formedness. <a href="#refsXML">[XML]</a>
   <a href="#refsXMLNS">[XMLNS]</a>
  </dl>


  <h3 id="extensibility"><span class="secno">2.2 </span>Extensibility</h3>

  <p>User agents, Working Groups, and other interested parties are
  <em>strongly encouraged</em> to discuss extensions on a relevant public
  forum, preferably
  <a href="mailto:public-webapps@w3.org">public-webapps@w3.org</a>. If this
  is for some reason not possible prefix the extension in some way and start
  the prefix with an uppercase letter. E.g. if company Foo wants to add a
  private method <code>bar()</code> it could be named <code>FooBar()</code>
  to prevent clashes with a potential future standardized
  <code>bar()</code>.</p>



  <h2 id="terminology"><span class="secno">3 </span>Terminology</h2>


  <p>The term <dfn id="user-credentials">user credentials</dfn> for the purposes of this
  specification means cookies, HTTP authentication, and client-side SSL
  certificates. Specifically it does not refer to proxy authentication or
  the <code title="http-origin">Origin</code> header.
  <a href="#refsCOOKIES">[COOKIES]</a> <!-- XXX ref? --></p>


  <p>To <dfn id="deflate-a-domstring-into-a-byte-sequence">deflate a DOMString into a byte sequence</dfn> means to create
  a sequence of bytes such that the <var title="">n</var>th byte of the
  sequence is equal to the low-order byte of the <var title="">n</var>th
  code point in the original DOMString.</p>

  <p>To <dfn id="inflate-a-byte-sequence-into-a-domstring">inflate a byte sequence into a DOMString</dfn> means to create
  a DOMString such that the <var title="">n</var>th code point has 0x00 as
  the high-order byte and the <var title="">n</var>th byte of the byte
  sequence as the low-order byte.</p>



  <h2 id="the-xmlhttprequest-interface"><span class="secno">4 </span>The <code title="">XMLHttpRequest</code> Interface</h2>

  <p>The <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object can be used by scripts to issue
  HTTP requests.</p>

  <pre class="idl">[NoInterfaceObject]
interface <dfn id="xmlhttprequesteventtarget">XMLHttpRequestEventTarget</dfn> : <a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#eventtarget">EventTarget</a> {
  // <a href="#event-handlers">event handlers</a>
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-onloadstart" title="handler-xhr-onloadstart">onloadstart</a>;
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-onprogress" title="handler-xhr-onprogress">onprogress</a>;
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-onabort" title="handler-xhr-onabort">onabort</a>;
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-onerror" title="handler-xhr-onerror">onerror</a>;
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-onload" title="handler-xhr-onload">onload</a>;
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-ontimeout" title="handler-xhr-ontimeout">ontimeout</a>;
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-onloadend" title="handler-xhr-onloadend">onloadend</a>;
};

interface <dfn id="xmlhttprequestupload">XMLHttpRequestUpload</dfn> : <a href="#xmlhttprequesteventtarget">XMLHttpRequestEventTarget</a> {

};

[<a href="#dom-xmlhttprequest" title="dom-XMLHttpRequest">Constructor</a>]
interface <dfn id="xmlhttprequest">XMLHttpRequest</dfn> : <a href="#xmlhttprequesteventtarget">XMLHttpRequestEventTarget</a> {
  // <a href="#event-handlers">event handler</a>
           attribute <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#function">Function</a> <a href="#handler-xhr-onreadystatechange" title="handler-xhr-onreadystatechange">onreadystatechange</a>;

  // <a href="#states">states</a>
  const unsigned short <a href="#dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT">UNSENT</a> = 0;
  const unsigned short <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> = 1;
  const unsigned short <a href="#dom-xmlhttprequest-headers_received" title="dom-XMLHttpRequest-HEADERS_RECEIVED">HEADERS_RECEIVED</a> = 2;
  const unsigned short <a href="#dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING">LOADING</a> = 3;
  const unsigned short <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a> = 4;
  readonly attribute unsigned short <a href="#dom-xmlhttprequest-readystate" title="dom-XMLHttpRequest-readyState">readyState</a>;

  // <a href="#request">request</a>
  void <a href="#dom-xmlhttprequest-open" title="dom-XMLHttpRequest-open">open</a>(DOMString <var>method</var>, DOMString <var title="">url</var>);
  void <a href="#dom-xmlhttprequest-open" title="dom-XMLHttpRequest-open">open</a>(DOMString <var>method</var>, DOMString <var title="">url</var>, boolean <var>async</var>);
  void <a href="#dom-xmlhttprequest-open" title="dom-XMLHttpRequest-open">open</a>(DOMString <var>method</var>, DOMString <var title="">url</var>, boolean <var>async</var>, DOMString? <var>user</var>);
  void <a href="#dom-xmlhttprequest-open" title="dom-XMLHttpRequest-open">open</a>(DOMString <var>method</var>, DOMString <var title="">url</var>, boolean <var>async</var>, DOMString? <var>user</var>, DOMString? <var>password</var>);
  void <a href="#dom-xmlhttprequest-setrequestheader" title="dom-XMLHttpRequest-setRequestHeader">setRequestHeader</a>(DOMString <var>header</var>, DOMString <var>value</var>);
           attribute unsigned long <a href="#dom-xmlhttprequest-timeout" title="dom-XMLHttpRequest-timeout">timeout</a>;
           attribute boolean <a href="#dom-xmlhttprequest-withcredentials" title="dom-XMLHttpRequest-withCredentials">withCredentials</a>;
  readonly attribute <a href="#xmlhttprequestupload">XMLHttpRequestUpload</a> <a href="#dom-xmlhttprequest-upload" title="dom-XMLHttpRequest-upload">upload</a>;
  void <a href="#dom-xmlhttprequest-send" title="dom-XMLHttpRequest-send">send</a>();
  void <a href="#dom-xmlhttprequest-send" title="dom-XMLHttpRequest-send">send</a>(<a class="external" href="http://www.khronos.org/registry/typedarray/specs/latest/#5">ArrayBuffer</a> <var>data</var>);
  void <a href="#dom-xmlhttprequest-send" title="dom-XMLHttpRequest-send">send</a>(<a class="external" href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a> <var>data</var>);
  void <a href="#dom-xmlhttprequest-send" title="dom-XMLHttpRequest-send">send</a>(<a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a> <var>data</var>);
  void <a href="#dom-xmlhttprequest-send" title="dom-XMLHttpRequest-send">send</a>([AllowAny] DOMString? <var>data</var>);
  void <a href="#dom-xmlhttprequest-send" title="dom-XMLHttpRequest-send">send</a>(<a href="#formdata">FormData</a> <var>data</var>);
  void <a href="#dom-xmlhttprequest-abort" title="dom-XMLHttpRequest-abort">abort</a>();

  // <a href="#response">response</a>
  readonly attribute unsigned short <a href="#dom-xmlhttprequest-status" title="dom-XMLHttpRequest-status">status</a>;
  readonly attribute DOMString <a href="#dom-xmlhttprequest-statustext" title="dom-XMLHttpRequest-statusText">statusText</a>;
  DOMString <a href="#dom-xmlhttprequest-getresponseheader" title="dom-XMLHttpRequest-getResponseHeader">getResponseHeader</a>(DOMString <var>header</var>);
  DOMString <a href="#dom-xmlhttprequest-getallresponseheaders" title="dom-XMLHttpRequest-getAllResponseHeaders">getAllResponseHeaders</a>();
  void <a href="#dom-xmlhttprequest-overridemimetype" title="dom-XMLHttpRequest-overrideMimeType">overrideMimeType</a>(DOMString <var>mime</var>);
           attribute DOMString <a href="#dom-xmlhttprequest-responsetype" title="dom-XMLHttpRequest-responseType">responseType</a>;
  readonly attribute any <a href="#dom-xmlhttprequest-response" title="dom-XMLHttpRequest-response">response</a>;
  readonly attribute DOMString <a href="#dom-xmlhttprequest-responsetext" title="dom-XMLHttpRequest-responseText">responseText</a>;
  readonly attribute <span>Document</span> <a href="#dom-xmlhttprequest-responsexml" title="dom-XMLHttpRequest-responseXML">responseXML</a>;
};

[<a href="#dom-anonxmlhttprequest" title="dom-AnonXMLHttpRequest">Constructor</a>]
interface <dfn id="anonxmlhttprequest">AnonXMLHttpRequest</dfn> : <a href="#xmlhttprequest">XMLHttpRequest</a> {
};</pre>



  <h3 id="origin-and-base-url"><span class="secno">4.1 </span>Origin and Base URL</h3>

  <p>Each <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object has an associated
  <dfn id="xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</dfn> and an
  <dfn id="xmlhttprequest-base-url"><code>XMLHttpRequest</code> base URL</dfn>.

  <p>This specification defines their values when the global object is
  represented by the <code class="external"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#window">Window</a></code> object. When
  the <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object is used in other contexts their
  values will have to be defined as appropriate for that context. That is
  considered to be out of scope for this specification.</p>

  <p>In environments where the global object is represented by the
  <code class="external"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#window">Window</a></code> object the
  <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object has an associated
  <dfn id="xmlhttprequest-document"><code>XMLHttpRequest</code> <code>Document</code></dfn> which is the
  <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code> object associated with the
  <code class="external"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#window">Window</a></code> object for which the
  <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> interface object was created.</p>

  <p class="note">The
  <a href="#xmlhttprequest-document"><code>XMLHttpRequest</code> <code>Document</code></a> is used to
  determine the <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> and
  <a href="#xmlhttprequest-base-url"><code>XMLHttpRequest</code> base URL</a> at a later stage.</p>



  <h3 id="task-sources"><span class="secno">4.2 </span>Task Sources</h3>

  <p>The <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#task-source">task source</a> used by this
  specification is the <dfn id="xmlhttprequest-task-source"><code>XMLHttpRequest</code> task source</dfn>.


  <h3 id="constructors"><span class="secno">4.3 </span>Constructors</h3>


  <p>The <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object has an associated
  <dfn id="anonymous-flag">anonymous flag</dfn>. When set to true <a href="#user-credentials">user credentials</a>
  and the <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> are not exposed
  when <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#fetch" title="fetch">fetching</a> resources. It
  is false by default and can only be set to true by using the
  <code title="dom-AnonXMLHttpRequest"><a href="#dom-anonxmlhttprequest">AnonXMLHttpRequest()</a></code>
  constructor.</p>


  <dl class="domintro">
   <dt><var title="">client</var> = new <code title="dom-XMLHttpRequest"><a href="#dom-xmlhttprequest">XMLHttpRequest</a></code>()</dt>
   <dd>Returns a new <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object.</dd>

   <dt><var title="">client</var> = new <code title="dom-AnonXMLHttpRequest"><a href="#dom-anonxmlhttprequest">AnonXMLHttpRequest</a></code>()</dt>
   <dd>Returns a new <code><a href="#anonxmlhttprequest">AnonXMLHttpRequest</a></code> object that has the
   <a href="#anonymous-flag">anonymous flag</a> set to true.</dd>

  </dl>

  <p>When the
  <dfn id="dom-xmlhttprequest" title="dom-XMLHttpRequest"><code>XMLHttpRequest()</code></dfn>
  constructor is invoked, the user agent must return a new
  <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object.</p>


  <p>When the
  <dfn id="dom-anonxmlhttprequest" title="dom-AnonXMLHttpRequest"><code>AnonXMLHttpRequest()</code></dfn>
  constructor is invoked, the user agent must return a new
  <code><a href="#anonxmlhttprequest">AnonXMLHttpRequest</a></code> object with its
  <a href="#anonymous-flag">anonymous flag</a> set to true.</p>


  <h3 id="event-handlers"><span class="secno">4.4 </span>Event Handlers</h3>


  <p>The following are the
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handlers">event handlers</a> (and their corresponding
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handler-event-type" title="event handler event type">event handler event types</a>)
  that must be supported on objects implementing an interface that inherits
  from <code><a href="#xmlhttprequesteventtarget">XMLHttpRequestEventTarget</a></code> as attributes:</p>

  <table>
   <thead>
    <tr>
     <th><a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handlers" title="event handlers">event handler</a>
     <th><a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handler-event-type">event handler event type</a>
   <tbody>
    <tr>
     <td><dfn id="handler-xhr-onloadstart" title="handler-xhr-onloadstart"><code>onloadstart</code></dfn>
     <td><code title="event-xhr-loadstart"><a href="#event-xhr-loadstart">loadstart</a></code>
    <tr>
     <td><dfn id="handler-xhr-onprogress" title="handler-xhr-onprogress"><code>onprogress</code></dfn>
     <td><code title="event-xhr-progress"><a href="#event-xhr-progress">progress</a></code>
    <tr>
     <td><dfn id="handler-xhr-onabort" title="handler-xhr-onabort"><code>onabort</code></dfn>
     <td><code title="event-xhr-abort"><a href="#event-xhr-abort">abort</a></code>
    <tr>
     <td><dfn id="handler-xhr-onerror" title="handler-xhr-onerror"><code>onerror</code></dfn>
     <td><code title="event-xhr-error"><a href="#event-xhr-error">error</a></code>
    <tr>
     <td><dfn id="handler-xhr-onload" title="handler-xhr-onload"><code>onload</code></dfn>
     <td><code title="event-xhr-load"><a href="#event-xhr-load">load</a></code>
    <tr>
     <td><dfn id="handler-xhr-ontimeout" title="handler-xhr-ontimeout"><code>ontimeout</code></dfn>
     <td><code title="event-xhr-timeout"><a href="#event-xhr-timeout">timeout</a></code>
    <tr>
     <td><dfn id="handler-xhr-onloadend" title="handler-xhr-onloadend"><code>onloadend</code></dfn>
     <td><code title="event-xhr-loadend"><a href="#event-xhr-loadend">loadend</a></code>
  </table>


  <p>The following is the
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handlers" title="event handlers">event handler</a>
  (and its corresponding
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handler-event-type">event handler event type</a>) that must be
  supported as attribute solely by the
  <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object:</p>

  <table>
   <thead>
    <tr>
     <th><a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handlers" title="event handlers">event handler</a>
     <th><a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#event-handler-event-type">event handler event type</a>
   <tbody>
    <tr>
     <td><dfn id="handler-xhr-onreadystatechange" title="handler-xhr-onreadystatechange"><code>onreadystatechange</code></dfn>
     <td><code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code></td>
  </table>


  <h3 id="states"><span class="secno">4.5 </span>States</h3>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-readyState"><a href="#dom-xmlhttprequest-readystate">readyState</a></code></dt>
   <dd><p>Returns the current state.</dd>
  </dl>

  <p>The <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object can be in several states. The
  <dfn id="dom-xmlhttprequest-readystate" title="dom-XMLHttpRequest-readyState"><code>readyState</code></dfn>
  attribute must return the current state, which must be one of the
  following values:</p>

  <dl>
   <dt><dfn id="dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT"><code>UNSENT</code></dfn>
   (numeric value 0)</dt>
   <dd><p>The object has been constructed.</dd>

   <dt><dfn id="dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED"><code>OPENED</code></dfn>
   (numeric value 1)</dt>
   <dd><p>The <code title="dom-XMLHttpRequest-open"><a href="#dom-xmlhttprequest-open">open()</a></code> method has been successfully invoked.
   During this state request headers can be set using
   <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>
   and the request can be made using the
   <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code> method.</dd>

   <dt><dfn id="dom-xmlhttprequest-headers_received" title="dom-XMLHttpRequest-HEADERS_RECEIVED"><code>HEADERS_RECEIVED</code></dfn>
   (numeric value 2)</dt>
   <dd><p>All redirects (if any) have been followed and all HTTP headers of
   the final response have been received. Several response members of the
   object are now available.</dd>

   <dt><dfn id="dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING"><code>LOADING</code></dfn>
   (numeric value 3)</dt>
   <dd><p>The <a href="#response-entity-body">response entity body</a> is being received.</dd>

   <dt><dfn id="dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE"><code>DONE</code></dfn>
   (numeric value 4)</dt>
   <dd><p>The data transfer has been completed or something went wrong
   during the transfer (e.g. infinite redirects).</dd>
  </dl>

  <p>The <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> state has an associated
  <dfn id="send-flag"><code>send()</code> flag</dfn> that indicates whether
  the <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code> method has been
  invoked. It can be either true or false and has an initial value of
  false.</p>

  <p>The <dfn id="error-flag">error flag</dfn> indicates some type of
  network error or abortion. It is used during the
  <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a> state. It can be either
  true or false and has an initial value of false.</p>


  <h3 id="request"><span class="secno">4.6 </span>Request</h3>

  <p>The <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object holds the following request
  metadata variables:</p>

  <dl>
   <dt>The <dfn id="asynchronous-flag">asynchronous flag</dfn></dt>
   <dd>True when <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#fetch" title="fetch">fetching</a> is
   done asychronously. False when fetching is done synchronously.</dd>

   <dt>The <dfn id="request-method">request method</dfn></dt>
   <dd>The HTTP method used in the request.</dd>

   <dt>The <dfn id="request-url">request URL</dfn></dt>
   <dd>The resolved <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#url">URL</a> used in the
   request.</dd>

   <dt>The <dfn id="request-username">request username</dfn></dt>
   <dd>The username used in the request or null if there is no
   username.</dd>

   <dt>The <dfn id="request-password">request password</dfn></dt>
   <dd>The password used in the request or null if there is no
   password.</dd>

   <dt>The <dfn id="author-request-headers">author request headers</dfn></dt>
   <dd>A list consisting of HTTP header name/value pairs to be used in the
   request.<p></p>

   <dt>The <dfn id="request-entity-body">request entity body</dfn></dt>
   <dd>The <a class="external" href="http://tools.ietf.org/html/rfc2616/#section-7.2">entity body</a> used in the
   request or null if there is no
   <a class="external" href="http://tools.ietf.org/html/rfc2616/#section-7.2">entity body</a>.</dd>


   <dt>The <dfn id="upload-complete-flag">upload complete flag</dfn></dt>
   <dd>Used to determine when to stop sending upload progress events. The
   flag is either true or false.</dd>

   <dt>The <dfn id="upload-events-flag">upload events flag</dfn></dt>
   <dd>Used to determine whether to send upload progress events for
   cross-origin requests. The flag is either true or false.</dd>

  </dl>


  <p>The <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object also has an associated
  <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object.</p>



  <h4 id="the-open-method"><span class="secno">4.6.1 </span>The <code title="">open()</code> method</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-open"><a href="#dom-xmlhttprequest-open">open(<var title="">method</var>,
   <var title="">url</var>, <var title="">async</var>, <var title="">user</var>,
   <var title="">password</var>)</a></code></dt>

   <dd>
    <p>Sets the <a href="#request-method">request method</a>, <a href="#request-url">request URL</a>,
    <a href="#asynchronous-flag">asynchronous flag</a>, <a href="#request-username">request username</a>, and
    <a href="#request-password">request password</a>.</p>

    <p>Throws a <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code> exception if one of the following is
    true:</p>

    <ul>
     <li><var title="">method</var> is not a valid HTTP method.</li>
     <li><var title="">url</var> cannot be resolved.</li>
     <li><var title="">url</var> contains the <code>"user:password"</code>
     format in the <code class="external"><a href="http://tools.ietf.org/html/rfc2616/#section-3.2.1">userinfo</a></code> production.
    </ul>

    <p>Throws a <code class="external" title="dom-DOMException-SECURITY_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-security_err">SECURITY_ERR</a></code> exception if
    <var title="">method</var> is a case-insensitive match for
    <code>CONNECT</code>, <code>TRACE</code> or <code>TRACK</code>.</p>

    <p>Throws an <code class="external" title="dom-DOMException-INVALID_ACCESS_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception if either
    <var title="">user</var> or <var title="">password</var> is passed as
    argument and the <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#origin">origin</a> of <var title="">url</var> does not
    match the <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a>.</p>
   </dd>
  </dl>

  <p>When the
  <dfn id="dom-xmlhttprequest-open" title="dom-XMLHttpRequest-open"><code>open(<var title="">method</var>, <var title="">url</var>, <var title="">async</var>, <var title="">user</var>, <var title="">password</var>)</code></dfn>
  method is invoked, the user agent must run these steps
  (unless otherwise indicated):</p>

  <ol>
   <li>
    <p>If the <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object has an associated
    <a href="#xmlhttprequest-document"><code>XMLHttpRequest</code> <code>Document</code></a> run
    these substeps:</p>

    <ol>
     <li><p>If the
     <a href="#xmlhttprequest-document"><code>XMLHttpRequest</code> <code>Document</code></a> is not
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/browsers.html#fully-active">fully active</a> raise an
     <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code>
     exception and terminate the overall set of steps.</li>

     <li><p>Let <a href="#xmlhttprequest-base-url"><code>XMLHttpRequest</code> base URL</a> be the
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#document-base-url">document base URL</a> of the
     <a href="#xmlhttprequest-document"><code>XMLHttpRequest</code> <code>Document</code></a>.</li>

     <li><p>Let <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> be the
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#origin">origin</a> of the
     <a href="#xmlhttprequest-document"><code>XMLHttpRequest</code> <code>Document</code></a>
     if the <a href="#anonymous-flag">anonymous flag</a> is false and let it be a globally
     unique identifier if the <a href="#anonymous-flag">anonymous flag</a> is true.</li>
    </ol>
   </li>

   <li><p>If any code point in <var>method</var> is higher than
   U+00FF LATIN SMALL LETTER Y WITH DIAERESIS or after
   <a href="#deflate-a-domstring-into-a-byte-sequence" title="deflate a DOMString into a byte sequence">deflating</a>
   <var>method</var> it does not match the
   <a class="external" href="http://tools.ietf.org/html/rfc2616/#section-5.1.1">Method</a> token production raise a <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code>
   exception and terminate these steps. Otherwise let <var>method</var> be
   the result of
   <a href="#deflate-a-domstring-into-a-byte-sequence" title="deflate a DOMString into a byte sequence">deflating</a>
   <var>method</var>.</li> <!-- This sounds lame, but it works. -->

   <li>
    <p>If <var>method</var> is a case-insensitive match for
    <code>CONNECT</code>, <code>DELETE</code>, <code>GET</code>,
    <code>HEAD</code>, <code>OPTIONS</code>, <code>POST</code>,
    <code>PUT</code>, <code>TRACE</code>, or <code>TRACK</code>
    subtract 0x20 from each byte in the range 0x61 (ASCII a) to
    0x7A (ASCII z).</p>

    <p class="note">If it does not match any of the above, it is passed
    through <em>literally</em>, including in the final request.</p>
   </li>
   <!-- WebKit (and supposedly Gecko) also uppercase: COPY, INDEX, LOCK,
   M-POST, MKCOL, MOVE, PROPFIND, PROPPATCH, and UNLOCK. -->

   <li>
    <p>If <var>method</var> is a case-sensitive match for
    <code>CONNECT</code>, <code>TRACE</code>, or <code>TRACK</code>  raise a
    <code class="external" title="dom-DOMException-SECURITY_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-security_err">SECURITY_ERR</a></code> exception and terminate these steps.</p>

    <p class="note">Allowing these methods poses a security risk.
    <a href="#refsHTTPVERBSEC">[HTTPVERBSEC]</a>
   </li>

   <li><p>Let <var title="">url</var> be a
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#url">URL</a> with character encoding UTF-8.

   <li><p><span title="Resolve a URL">Resolve</span> <var title="">url</var>
   relative to the <a href="#xmlhttprequest-base-url"><code>XMLHttpRequest</code> base URL</a>.
   If the algorithm returns an error raise a <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code>
   exception and terminate these steps.</li>

   <!-- Presto and Gecko override the encoding. WebKit does not. Trident
   does not support non-ASCII URLs. This matters for the <query> component,
   see HTML. -->

   <li><p>Drop
   <code class="external" title="url-fragment"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#url-fragment">&lt;fragment&gt;</a></code> from
   <var title="">url</var>.</li>

   <li><p>If the <code>"user:password"</code> format in the
   <code class="external"><a href="http://tools.ietf.org/html/rfc2616/#section-3.2.1">userinfo</a></code> production is not supported
   for the relevant
   <code class="external" title="url-scheme"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#url-scheme">&lt;scheme&gt;</a></code> and
   <var title="">url</var> contains this format raise a
   <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code>
   and terminate these steps.</li>

   <!-- XXX need to throw here for "user:password" or just "user" for
            cross-origin unless we solve this in another way -->

   <li><p>If <var title="">url</var> contains the <code>"user:password"</code>
   format let <var>temp user</var> be the user part and
   <var>temp password</var> be the password part.</li>

   <li><p>If <var title="">url</var> just contains the <code>"user"</code>
   format let <var>temp user</var> be the user part.</li>

   <li><p>Let <var>async</var> be the value of the <var>async</var> argument
   or true if it was omitted.</li>

   <li>
    <p>If the <var title="">user</var> argument was not omitted follow these
    sub steps:</p>

    <ol>
     <li><p>If <var title="">user</var> is not null and the
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#origin">origin</a> of <var title="">url</var> is not
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin">same origin</a> with the
     <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> raise an
     <code class="external" title="dom-DOMException-INVALID_ACCESS_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and terminate the overall set
     of steps.</li>

     <li><p>Let <var>temp user</var> be <var>user</var>.</li>
    </ol>

    <p class="note">These steps override anything that may have been set by
    the <var title="">url</var> argument.</p>
   </li>

   <li>
    <p>If the <var title="">password</var> argument was not omitted follow
    these sub steps:</p>

    <ol>
     <li><p>If <var title="">password</var> is not null and the
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#origin">origin</a> of <var title="">url</var> is not
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin">same origin</a> with the
     <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> raise an
     <code class="external" title="dom-DOMException-INVALID_ACCESS_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and terminate the overall set
     of steps.</li>

     <li><p>Let <var>temp password</var> be <var>password</var>.</li>
    </ol>

    <p class="note">These steps override anything that may have been set by
    the <var title="">url</var> argument.</p>
   </li>

   <li><p><a href="#terminate-abort" title="terminate abort()">Terminate the <code>abort()</code> algorithm</a>.</li>

   <li><p><a href="#terminate-send" title="terminate send()">Terminate the <code>send()</code> algorithm</a>.</li>

   <li><p>The user agent should cancel any network
   activity for which the object is responsible.</li>
   <!-- we can hardly require it... -->

   <li><p>If there are any
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#concept-task" title="concept-task">tasks</a> from the
   object's <a href="#xmlhttprequest-task-source"><code>XMLHttpRequest</code> task source</a> in one of
   the <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#task-queue" title="task queue">task queues</a>,
   then remove them.

   <li>
    <p>Set variables associated with the object as follows:</p>

    <ul>

     <li><p>Set the <a href="#request-method">request method</a> to <var>method</var>.</li>

     <li><p>Set the <a href="#request-url">request URL</a> to <var title="">url</var>.</li>

     <li><p>Set the <a href="#asynchronous-flag">asynchronous flag</a> to the value of
     <var>async</var>.</li>

     <li><p>Set the <a href="#request-username">request username</a> to <var>temp user</var>.</li>

     <li><p>Set the <a href="#request-password">request password</a> to <var>temp password</var>.</li>

     <li><p>Empty the list of <a href="#author-request-headers">author request headers</a>.</p>


     <li><p>Set the
     <code title="dom-XMLHttpRequest-withCredentials"><a href="#dom-xmlhttprequest-withcredentials">withCredentials</a></code>
     attribute's value to false.</li>

     <li><p>Set the
     <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code>
     attribute's value to the empty string.</li>


     <li><p>Set the <a href="#send-flag"><code>send()</code> flag</a> to false.</li>

     <li><p>Set <a href="#response-entity-body">response entity body</a> to null.</li>
    </ul>
   </li>

   <li><p>Switch the state to
   <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a>.</li>

   <li><p><a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-event-fire" title="concept-event-fire">Fire an event</a> named <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code>.</li>
  </ol>



  <h4 id="the-setrequestheader-method"><span class="secno">4.6.2 </span>The <code title="">setRequestHeader()</code> method</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader(<var title="">header</var>, <var title="">value</var>)</a></code></dt>

   <dd>
    <p>Appends an header to the list of
    <a href="#author-request-headers">author request headers</a>, or if <var>header</var> is already
    in the list of <a href="#author-request-headers">author request headers</a>, combines its value
    with <var>value</var>.</p>

    <p>Throws an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception if the state is
    not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> or if the
    <a href="#send-flag"><code>send()</code> flag</a> is true.</p>

    <p>Throws a <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code> exception if
    <var title="">header</var> is not a valid HTTP header field name or if
    <var title="">value</var> is not a valid HTTP header field value.</p>
   </dd>
  </dl>

  <p class="note">As indicated in the algorithm below certain headers cannot
  be set and are left up to the user agent. In addition there are certain
  other headers the user agent will take control of if they are not set by
  the author as indicated at the end of the
  <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code> method section.</p>


  <p class="note">For non <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin">same origin</a> requests using the HTTP
  <code>GET</code> method a preflight request is made when headers other
  than <code>Accept</code> and <code>Accept-Language</code> are set.</p>


  <p>When the
  <dfn id="dom-xmlhttprequest-setrequestheader" title="dom-XMLHttpRequest-setRequestHeader"><code>setRequestHeader(<var title="">header</var>, <var title="">value</var>)</code></dfn>
  method is invoked, the user agent must run these
  steps:</p>

  <ol>
   <li><p>If the state is not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> raise
   an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>If the <a href="#send-flag"><code>send()</code> flag</a> is true raise an
   <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>If any code point in <var>header</var> is higher than
   U+00FF LATIN SMALL LETTER Y WITH DIAERESIS or after
   <a href="#deflate-a-domstring-into-a-byte-sequence" title="deflate a DOMString into a byte sequence">deflating</a>
   <var>header</var> it does not match the
   <a class="external" href="http://tools.ietf.org/html/rfc2616/#section-4.2">field-name</a> production raise a
   <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code>
   exception and terminate these steps. Otherwise let <var>header</var> be
   the result of
   <a href="#deflate-a-domstring-into-a-byte-sequence" title="deflate a DOMString into a byte sequence">deflating</a>
   <var>header</var>.</li> <!-- This sounds lame, but it works. -->

   <li>
    <p>If any code point in <var>value</var> is higher than
    U+00FF LATIN SMALL LETTER Y WITH DIAERESIS or after
    <a href="#deflate-a-domstring-into-a-byte-sequence" title="deflate a DOMString into a byte sequence">deflating</a>
    <var>value</var> it does not match the
    <a class="external" href="http://tools.ietf.org/html/rfc2616/#section-4.2">field-value</a> production raise a
    <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code>
    exception and terminate these steps. Otherwise let <var>value</var> be
    the result of
    <a href="#deflate-a-domstring-into-a-byte-sequence" title="deflate a DOMString into a byte sequence">deflating</a>
    <var>value</var>.</p> <!-- This sounds lame, but it works. -->

    <p class="note">The empty string is legal and represents the empty
    header value.</p>
   </li>

   <li>
    <p>Terminate these steps if <var>header</var> is a case-insensitive
    match for one of the following headers:</p>

    <ul>
     <li><code>Accept-Charset</code></li>
     <li><code>Accept-Encoding</code></li>
     <li><code>Access-Control-Request-Headers</code></li>
     <li><code>Access-Control-Request-Method</code></li>
     <li><code>Connection</code></li>
     <li><code>Content-Length</code></li>
     <li><code>Cookie</code></li>
     <li><code>Cookie2</code></li>
     <li><code>Content-Transfer-Encoding</code></li>
     <li><code>Date</code></li>
     <li><code>Expect</code></li>
     <li><code>Host</code></li>
     <li><code>Keep-Alive</code></li>
     <li><code title="">Origin</code></li>
     <li><code>Referer</code></li>
     <li><code>TE</code></li>
     <li><code>Trailer</code></li>
     <li><code>Transfer-Encoding</code></li>
     <li><code>Upgrade</code></li>
     <li><code>User-Agent</code></li>
     <li><code>Via</code></li>
    </ul>

    <p>&hellip; or if the start of <var>header</var> is a case-insensitive
    match for <code>Proxy-</code> or <code>Sec-</code> (including when
    <var>header</var> is just <code>Proxy-</code> or <code>Sec-</code>).</p>

    <p class="note">The above headers are controlled by the user agent to
    let it control those aspects of transport. This guarantees data
    integrity to some extent. Header names starting with <code>Sec-</code>
    are not allowed to be set to allow new headers to be minted that are
    guaranteed not to come from <code><a href="#xmlhttprequest">XMLHttpRequest</a></code>.</p>
   </li>

   <li><p>If <var>header</var> is not in the
   <a href="#author-request-headers">author request headers</a> list append <var>header</var> with
   its associated <var>value</var> to the list and terminate these
   steps.</li>

   <li><p>If <var>header</var> is in the <a href="#author-request-headers">author request headers</a>
   list either use multiple headers, combine the values or use a combination
   of those (section 4.2, RFC 2616).
   <a href="#refsHTTP">[HTTP]</a>
   <!-- XXX it seems UAs always combine the values -->
  </ol>

  <p class="note">See also the
  <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code> method regarding user
  agent header handling for caching, authentication, proxies, and
  cookies.</p>

  <div class="example">
   <p>Some simple code demonstrating what happens when setting the same
   header twice:</p>

   <pre><code>// The following script:
var client = new XMLHttpRequest();
client.open('GET', 'demo.cgi');
client.setRequestHeader('X-Test', 'one');
client.setRequestHeader('X-Test', 'two');
client.send();

// &hellip;results in the following header being sent:
X-Test: one, two</code></pre>
  </div>


  <h4 id="the-timeout-attribute"><span class="secno">4.6.3 </span>The <code title="">timeout</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-timeout"><a href="#dom-xmlhttprequest-timeout">timeout</a></code></dt>
   <dd>
    <p>The amount of milliseconds a request can take before being
    terminated. Initially zero. Zero means there is no timeout.</p>
   </dd>
  </dl>

  <p>On setting the
  <dfn id="dom-xmlhttprequest-timeout" title="dom-XMLHttpRequest-timeout"><code>timeout</code></dfn>
  attribute its value must be set to the given value.</p>

  <p>On getting, the <code title="dom-XMLHttpRequest-timeout"><a href="#dom-xmlhttprequest-timeout">timeout</a></code>
  attribute must return its value.</p>


  <h4 id="the-withcredentials-attribute"><span class="secno">4.6.4 </span>The <code title="">withCredentials</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-withCredentials"><a href="#dom-xmlhttprequest-withcredentials">withCredentials</a></code></dt>
   <dd>
    <p>True when <a href="#user-credentials">user credentials</a> are to be included in a
    cross-origin request. False when they are to be excluded in a
    cross-origin request and when cookies are to be ignored in its response.
    Initially false.

    <p>When set: throws an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception if the
    state is not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> or if
    the <a href="#send-flag"><code>send()</code> flag</a> is true.</p>
    <p>When set: throws an <code class="external" title="dom-DOMException-INVALID_ACCESS_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception if the
    <a href="#anonymous-flag">anonymous flag</a> is true.</p>
   </dd>
  </dl>

  <p>On setting the
  <dfn id="dom-xmlhttprequest-withcredentials" title="dom-XMLHttpRequest-withCredentials"><code>withCredentials</code></dfn>
  attribute these steps must be run:</p>

  <ol>
   <li><p>If the state is not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> raise
   an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>If the <a href="#send-flag"><code>send()</code> flag</a> is true raise an
   <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>If the <a href="#anonymous-flag">anonymous flag</a> is true raise an
   <code class="external" title="dom-DOMException-INVALID_ACCESS_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>Set the
   <code title="dom-XMLHttpRequest-withCredentials"><a href="#dom-xmlhttprequest-withcredentials">withCredentials</a></code>
   attribute's value to the given value.</li>
  </ol>

  <p>On getting the
  <code title="dom-XMLHttpRequest-withCredentials"><a href="#dom-xmlhttprequest-withcredentials">withCredentials</a></code>
  attribute it must return its value.</p>

  <p class="note">The
  <code title="dom-XMLHttpRequest-withCredentials"><a href="#dom-xmlhttprequest-withcredentials">withCredentials</a></code>
  attribute has no effect when
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#fetch" title="fetch">fetching</a>
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin" title="same origin">same-origin</a>
  resources.</p>


  <h4 id="the-upload-attribute"><span class="secno">4.6.5 </span>The <code title="">upload</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-upload"><a href="#dom-xmlhttprequest-upload">upload</a></code></dt>
   <dd><p>Returns the associated <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code>
   object.</dd>
  </dl>

  <p>The
  <dfn id="dom-xmlhttprequest-upload" title="dom-XMLHttpRequest-upload"><code>upload</code></dfn>
  attribute must return the associated
  <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object.</p>



  <h4 id="the-send-method"><span class="secno">4.6.6 </span>The <code title="">send()</code> method</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send(<var title="">data</var>)</a></code></dt>
   <dd>
    <p>Initiates the request. The optional argument provides the
    <a href="#request-entity-body">request entity body</a>. The argument is ignored if
    <a href="#request-method">request method</a> is <code>GET</code> or
    <code>HEAD</code>.</p>

    <p>Throws an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception if the state is
    not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> or if the
    <a href="#send-flag"><code>send()</code> flag</a> is true.</p>
   </dd>
  </dl>

  <p>When the
  <dfn id="dom-xmlhttprequest-send" title="dom-XMLHttpRequest-send"><code>send(<var>data</var>)</code></dfn>
  method is invoked, the user agent must run these steps
  (unless otherwise noted). This algorithm can be
  <dfn id="terminate-send" title="terminate send()">terminated</dfn> by invoking the
  <code title="dom-XMLHttpRequest-open"><a href="#dom-xmlhttprequest-open">open()</a></code> or
  <code title="dom-XMLHttpRequest-abort"><a href="#dom-xmlhttprequest-abort">abort()</a></code> method. When it is
  <a href="#terminate-send" title="terminate send()">terminated</a> the user agent
  must terminate the algorithm after finishing the step
  it is on.</p>

  <p class="note">The <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code>
  algorithm can only be terminated when the <a href="#asynchronous-flag">asynchronous flag</a>
  is true and only after the method call has returned.</p>

  <ol>
   <li><p>If the state is not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> raise
   an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>If the <a href="#send-flag"><code>send()</code> flag</a> is true raise an
   <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li>
    <p>If the <a href="#request-method">request method</a> is a case-sensitive match for
    <code>GET</code> or <code>HEAD</code> act as if <var title="">data</var>
    is null.</p>

    <p>If the <var>data</var> argument has been omitted or is
    null, do not include a <a href="#request-entity-body">request entity body</a>
    and go to the next step.</p>

    <p>Otherwise, let <var>encoding</var> be null, <var>mime type</var> be
    null, and then follow these rules:</p>

    <dl class="switch">

     <dt>If <var>data</var> is a <code class="external"><a href="http://www.khronos.org/registry/typedarray/specs/latest/#5">ArrayBuffer</a></code></dt>
     <dd><p>Let the <a href="#request-entity-body">request entity body</a> be the raw data
     represented by <var>data</var>.</dd>

     <dt>If <var>data</var> is a <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a></code></dt>

     <dd>
      <p>If the object's
      <code class="external" title="dom-Blob-type"><a href="http://dev.w3.org/2006/webapi/FileAPI/#dfn-type">type</a></code>
      attribute is not the empty string let <var>mime type</var> be its
      value.</p>

      <p>Let the <a href="#request-entity-body">request entity body</a> be the raw data
      represented by <var>data</var>.</p>
     </dd>


     <dt>If <var>data</var> is a <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code>

     <dd>
      <p>Let <var>encoding</var> be the
      <a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#preferred-mime-name">preferred MIME name</a> of the
      <a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-document-character-encoding" title="concept-document-character-encoding">character encoding</a>
      of <var>data</var>. If <var>encoding</var> is UTF-16 change it to
      UTF-8.</p>

      <p>Let <var>mime type</var> be "<code>application/xml</code>" or
      "<code>text/html</code>" if
      <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code> is flagged as an
      <a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#html-document">HTML document</a>, followed by
      "<code>;charset=</code>", followed by <var>encoding</var>.</p>

      <p>Let the <a href="#request-entity-body">request entity body</a> be the result of getting
      the <code class="external" title="dom-innerHTML"><a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/content-models.html#dom-innerhtml">innerHTML</a></code>
      attribute on <var>data</var>
      <a class="external" href="http://dev.w3.org/2006/webapi/WebIDL/#dfn-obtain-unicode" title="convert a DOMString to a sequence of Unicode characters">converted to Unicode</a>
      and encoded as <var>encoding</var>. Re-raise any exception this
      raises.</p>

      <p class="note">In particular, if the document cannot be serialized an
      <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code>
      exception is raised.</p>

      <p class="note">Subsequent changes to the
      <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code> have no effect on what
      is transferred.</p>
     </dd>

     <dt>If <var>data</var> is a <code>DOMString</code></dt>

     <dd>
      <p>Let <var>encoding</var> be UTF-8.</p>

      <p>Let <var>mime type</var> be "<code>text/plain;charset=UTF-8</code>".</p>

      <p>Let the <a href="#request-entity-body">request entity body</a> be <var>data</var>
      <a class="external" href="http://dev.w3.org/2006/webapi/WebIDL/#dfn-obtain-unicode" title="convert a DOMString to a sequence of Unicode characters">converted to Unicode</a>
      and encoded as UTF-8.</p>
     </dd>


     <dt>If <var>data</var> is a <code><a href="#formdata">FormData</a></code></dt>

     <dd>
      <p>Let the <a href="#request-entity-body">request entity body</a> be the result of running
      the
      <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#multipart/form-data-encoding-algorithm"><code>multipart/form-data</code> encoding algorithm</a>
      with <var>data</var> as <var>form data set</var> and with UTF-8 as the
      explicit character encoding.</p>

      <p>Let <var>mime type</var> be the concatenation of
      "<code title="">multipart/form-data;</code>",
      a U+0020 SPACE character,
      "<code title="">boundary=</code>", and the
      <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#multipart/form-data-boundary-string"><code>multipart/form-data</code> boundary string</a>
      generated by the
      <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#multipart/form-data-encoding-algorithm"><code>multipart/form-data</code> encoding algorithm</a>.
     </dd>

    </dl>

    <p>If a <code>Content-Type</code> header is set using
    <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>
    whose value is a <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#valid-mime-type">valid MIME type</a> and
    has a <code>charset</code> parameter whose value is not a case-insensitive
    match for <var title="">encoding</var>, and <var title="">encoding</var>
    is not null, set all the <code>charset</code> parameters of the
    <code>Content-Type</code> header to <var title="">encoding</var>.</p>

    <p>If no <code>Content-Type</code> header has been set using
    <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>
    and <var title="">mime type</var> is not null set a
    <code>Content-Type</code> request header with as value
    <var title="">mime type</var>.</p>

    <!-- reminder: if we ever change this to always include charset it has
    to be included as the first parameter for compatibility reasons -->
   </li>

   <li><p>If the <a href="#asynchronous-flag">asynchronous flag</a> is false release the
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#storage-mutex">storage mutex</a>.</li>


   <li><p>If the <a href="#asynchronous-flag">asynchronous flag</a> is true and one or more
   event listeners are registered on the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code>
   object set the <a href="#upload-events-flag">upload events flag</a> to true. Otherwise, set
   the <a href="#upload-events-flag">upload events flag</a> to false.</li>


   <li><p>Set the <a href="#error-flag">error flag</a> to false.</li>


   <li><p>Set the <a href="#upload-complete-flag">upload complete flag</a> to true if there is no
   <a href="#request-entity-body">request entity body</a> or if the
   <a href="#request-entity-body">request entity body</a> is empty. Otherwise, set the
   <a href="#upload-complete-flag">upload complete flag</a> to false.</li>


   <li>
    <p>If the <a href="#asynchronous-flag">asynchronous flag</a> is true run these substeps:</p>

    <ol>
     <li><p>Set the <a href="#send-flag"><code>send()</code> flag</a> to true.</li>

     <li>
      <p><a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-event-fire" title="concept-event-fire">Fire an event</a> named <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code>.

      <p class="note">The state does not change. The event is dispatched for
      historical reasons.</p>
     </li>


     <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-loadstart"><a href="#event-xhr-loadstart">loadstart</a></code>.</li>

     <li><p>If the <a href="#upload-complete-flag">upload complete flag</a> is false
     <a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">fire a progress event</a> named <code title="event-xhr-loadstart"><a href="#event-xhr-loadstart">loadstart</a></code>
     on the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object.</li>


     <li><p>Return the <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code>
     method call, but continue running the steps in this algorithm.</li>
    </ol>
   </li>

   <li>
    <dl class="switch">
     <dt>If the <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> and the
     <a href="#request-url">request URL</a> are <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin">same origin</a></dt>

     <dd>
      <p>These are the <dfn id="same-origin-request-steps">same-origin request steps</dfn>.</p>

      <p><a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#fetch">Fetch</a> the
      <a href="#request-url">request URL</a> from <i title="">origin</i>
      <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a>, with the
      <i title="">synchronous flag</i> set if the
      <a href="#asynchronous-flag">asynchronous flag</a> is false, using HTTP method
      <a href="#request-method">request method</a>, user <a href="#request-username">request username</a> (if
      non-null) and password <a href="#request-password">request password</a> (if non-null),
      taking into account the <a href="#request-entity-body">request entity body</a>, list of
      <a href="#author-request-headers">author request headers</a> and the rules listed at the end of
      this section.</p>

      <dl class="switch">
       <dt>If the <a href="#asynchronous-flag">asynchronous flag</a> is false</dt>
       <dd>
        <p>While making the request also follow the
        <a href="#same-origin-request-event-rules">same-origin request event rules</a>.</p>

        <!--
         This cannot involve any task queue whatsoever because that would
         mean other tasks on the task queue might get processed as well
         which is counter to the whole idea of doing things synchronous.
        -->

        <p class="note">The
        <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code> method call will
        now be returned by virtue of this algorithm ending.</p>
       </dd>

       <dt>If the <a href="#asynchronous-flag">asynchronous flag</a> is true</dt>
       <dd>

        <p><a href="#make-upload-progress-notifications">Make upload progress notifications</a>.</p>

        <p><a href="#make-progress-notifications">Make progress notifications</a>.</p>


        <p>While processing the request, as data becomes available and when
        the user interferes with the request,
        <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task" title="queue a task">queue tasks</a>
        to update the <a href="#response-entity-body">response entity body</a> and follow the
        <a href="#same-origin-request-event-rules">same-origin request event rules</a>.</p>
       </dd>
      </dl>
     </dd>

     <dt>Otherwise</dt>
     <dd>
      <p>These are the <dfn id="cross-origin-request-steps">cross-origin request steps</dfn>.</p>




      <p>Make a <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request">cross-origin request</a>,
      passing these as parameters:</p>

      <dl>
       <dt>request URL</dt>
       <dd>The <a href="#request-url">request URL</a>.</dd>

       <dt>request method</dt>
       <dd>The <a href="#request-method">request method</a>.</dd>

       <dt>author request headers</dt>
       <dd>The list of <a href="#author-request-headers">author request headers</a>.</dd>

       <dt>request entity body</dt>
       <dd>The <a href="#request-entity-body">request entity body</a>.</dd>

       <dt>source origin</dt>
       <dd>The <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a>.</dd>

       <dt>credentials flag</dt>
       <dd>The
       <code title="dom-XMLHttpRequest-withCredentials"><a href="#dom-xmlhttprequest-withcredentials">withCredentials</a></code>
       attribute's value.</dd>

       <dt>force preflight flag</dt>
       <dd>The <a href="#upload-events-flag">upload events flag</a>.</dd>
      </dl>

      <p class="note"><a href="#request-username">Request username</a> and
      <a href="#request-password">request password</a> are always ignored as part of a
      <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request">cross-origin request</a>; including
      them would allow a site to perform a distributed password search.
      However, user agents will include <a href="#user-credentials">user credentials</a> in the
      request (if the user has any and if
      <code title="dom-XMLHttpRequest-withCredentials"><a href="#dom-xmlhttprequest-withcredentials">withCredentials</a></code>
      is true).</p>

      <dl class="switch">
       <dt>If the <a href="#asynchronous-flag">asynchronous flag</a> is false</dt>
       <dd>
        <p>While making the request also follow the
        <a href="#cross-origin-request-event-rules">cross-origin request event rules</a>.</p>

        <!--
         This cannot involve any task queue whatsoever because that would
         mean other tasks on the task queue might get processed as well
         which is counter to the whole idea of doing things synchronous.
        -->

        <p class="note">The
        <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code> method call will
        now be returned by virtue of this algorithm ending.</p>
       </dd>

       <dt>If the <a href="#asynchronous-flag">asynchronous flag</a> is true</dt>
       <dd>
        <p>While processing the request, as data becomes available and when
        the end user interferes with the request,
        <span title="queue a task">queue tasks</span> to update the
        <a href="#response-entity-body">response entity body</a> and follow the
        <a href="#cross-origin-request-event-rules">cross-origin request event rules</a>.</p>
       </dd>
      </dl>

     </dd>
    </dl>
   </li>
  </ol>

  <hr>

  <p>If the user agent allows the end user to configure a proxy it
  should modify the request appropriately; i.e., connect
  to the proxy host instead of the origin server, modify the
  <code>Request-Line</code> and send <code>Proxy-Authorization</code>
  headers as specified.</p>

  <hr>

  <p>If the user agent supports HTTP Authentication and
  <code title="http-authorization">Authorization</code> is not in the list
  of <a href="#author-request-headers">author request headers</a>, it should
  consider requests originating from the <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object
  to be part of the protection space that includes the accessed URIs and
  send <code title="http-authorization">Authorization</code> headers and
  handle <code>401 Unauthorized</code> requests appropriately.</p>

  <p>If authentication fails,
  <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> and the
  <a href="#request-url">request URL</a> are <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin">same origin</a>,
  <code title="http-authorization">Authorization</code> is not in the list
  of <a href="#author-request-headers">author request headers</a>, <a href="#request-username">request username</a> is
  null, and <a href="#request-password">request password</a> is null, user agents
  should prompt the end user for their username and
  password.</p>

  <p>Otherwise, if authentication fails, user agents
  must not prompt the end user for their username and
  password. <a href="#refsHTTPAUTH">[HTTPAUTH]</a>

  <p class="note">End users are not prompted for various cases so that
  authors can implement their own user interface.</p>

  <hr>

  <p>If the user agent supports HTTP State Management it
  should persist, discard and send cookies (as received
  in the <code>Set-Cookie</code> response header, and sent in the
  <code>Cookie</code> header) as applicable.
  <a href="#refsCOOKIES">[COOKIES]</a>

  <hr>

  <p>If the user agent implements a HTTP cache it should
  respect <code>Cache-Control</code> request headers set by the
  <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>
  (e.g., <code>Cache-Control: no-cache</code> bypasses the cache). It
  must not send <code>Cache-Control</code> or
  <code>Pragma</code> request headers automatically unless the end user
  explicitly requests such behavior (e.g. by reloading the page).</p>

  <p>For <code>304 Not Modified</code> responses that are a result of a
  user agent generated conditional request the user agent
  must act as if the server gave a <code>200 OK</code>
  response with the appropriate content. The user agent
  must allow
  <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>
  to override automatic cache validation by setting request headers (e.g.
  <code>If-None-Match</code> or <code>If-Modified-Since</code>), in which
  case <code>304 Not Modified</code> responses must be
  passed through. <a href="#refsHTTP">[HTTP]</a>

  <hr>

  <p>If the user agent implements server-driven content-negotiation
  it must follow these constraints for the
  <code>Accept</code> and <code>Accept-Language</code> request headers:</p>

  <ul>
   <li><p>Both headers must not be modified if they are
   already set through
   <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>.</li>

   <li><p>If not set through
   <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>
   <code>Accept-Language</code> should be set as
   appropriate.</li>

   <li><p>If not set through
   <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>
   <code>Accept</code> must be set with as value
   <code>*/*</code>.</li>
  </ul>

  <p>Responses must have the content-encodings
  automatically decoded. <a href="#refsHTTP">[HTTP]</a>

  <hr>

  <p>Besides the <a href="#author-request-headers">author request headers</a> user agents
  should not include additional request headers other than those mentioned
  above or other than those authors are not allowed to set using
  <code title="dom-XMLHttpRequest-setRequestHeader"><a href="#dom-xmlhttprequest-setrequestheader">setRequestHeader()</a></code>.
  This ensures that authors have a reasonably predictable API.</p>


  <h4 id="infrastructure-for-the-send-method"><span class="secno">4.6.7 </span>Infrastructure for the <code title="">send()</code> method</h4>

  <p>The <dfn id="same-origin-request-event-rules">same-origin request event rules</dfn> are as follows:</p>

  <dl class="switch">
   <dt>If the response has an HTTP status code of 301, 302, 303, or 307</dt>
   <dd>
    <p>If the redirect violates infinite loop precautions this is a
    <a href="#network-error">network error</a>.</p>

    <p>Otherwise, run these steps:</p>

    <ol>
     <li><p>Set the <a href="#request-url">request URL</a> to the
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/urls.html#url">URL</a> conveyed by the
     <code>Location</code> header.</li>

     <li><p>If the <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a> and the
     <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#origin">origin</a> of <a href="#request-url">request URL</a>
     are <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin">same origin</a> transparently follow
     the redirect while observing the
     <a href="#same-origin-request-event-rules">same-origin request event rules</a>.

     <li><p>Otherwise, follow the <a href="#cross-origin-request-steps">cross-origin request steps</a>
     and terminate the steps for this algorithm.</li>
    </ol>

    <p class="note">HTTP places requirements on the user agent regarding the
    preservation of the <a href="#request-method">request method</a> and
    <a href="#request-entity-body">request entity body</a> during redirects, and also requires end
    users to be notified of certain kinds of automatic redirections.</p>
    <!-- XXX HTTP needs fixing here -->
   </dd>

   <dt>If the end user cancels the request</dt>
   <dd><p>This is an <a href="#abort-error">abort error</a>.</dd>

   <dt>If there is a network error</dt>
   <dd>
    <p>In case of DNS errors, TLS negotiation failure, or other type of
    network errors, this is a <a href="#network-error">network error</a>. Do not request any
    kind of end user interaction.</p>

    <p class="note">This does not include HTTP responses that indicate
    some type of error, such as HTTP status code 410.</p>
   </dd>


   <dt>If <code title="dom-XMLHttpRequest-timeout"><a href="#dom-xmlhttprequest-timeout">timeout</a></code> is not 0
   and since the request started the amount of milliseconds specified by
   <code title="dom-XMLHttpRequest-timeout"><a href="#dom-xmlhttprequest-timeout">timeout</a></code> has passed</dt>
   <dd><p>This is a <a href="#timeout-error">timeout error</a>.</dd>


   <dt>Once all HTTP headers have been received, the
   <a href="#asynchronous-flag">asynchronous flag</a> is true, and the HTTP status code of the
   response is not 301, 302, 303, or 307</dt>
   <dd><p><a href="#switch-headers-received">Switch to the HEADERS_RECEIVED state</a>.</dd>

   <dt>Once the first byte (or more) of the
   <a href="#response-entity-body">response entity body</a> has been received and the
   <a href="#asynchronous-flag">asynchronous flag</a> is true</dt>
   <dt>If there is no <a href="#response-entity-body">response entity body</a> and the
   <a href="#asynchronous-flag">asynchronous flag</a> is true</dt>
   <dd><p><a href="#switch-loading">Switch to the LOADING state</a>.</dd>

   <dt>Once the whole <a href="#response-entity-body">response entity body</a> has been
   received</dt>
   <dt>If there is no <a href="#response-entity-body">response entity body</a> and the state is
   <a href="#dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING">LOADING</a></dt>
   <dt>If there is no <a href="#response-entity-body">response entity body</a> and the
   <a href="#asynchronous-flag">asynchronous flag</a> is false</dt>
   <dd><p><a href="#switch-done">Switch to the DONE state</a>.</dd>
  </dl>


  <hr>

  <p>The <dfn id="cross-origin-request-event-rules">cross-origin request event rules</dfn> are as follows:</p>

  <dl class="switch">
   <dt>If the <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a>
   is <i>preflight complete</i> and the <a href="#asynchronous-flag">asynchronous flag</a> is
   true</dt>
   <dd><p><a href="#make-upload-progress-notifications">Make upload progress notifications</a>.</dd>

   <dt>If the <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a>
   is <i title="">network error</i></dt>
   <dd><p>This is a <a href="#network-error">network error</a>.</dd>

   <dt>If the <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a>
   is <i title="">abort error</i></dt>
   <dd><p>This is an <a href="#abort-error">abort error</a>.</dd>

   <dt>If <code title="dom-XMLHttpRequest-timeout"><a href="#dom-xmlhttprequest-timeout">timeout</a></code> is not 0
   and since the request started the amount of milliseconds specified by
   <code title="dom-XMLHttpRequest-timeout"><a href="#dom-xmlhttprequest-timeout">timeout</a></code> has passed</dt>
   <dd><p>This is a <a href="#timeout-error">timeout error</a>.</dd>

   <dt>Once all HTTP headers have been received, the
   <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a> is
   <i>success</i>, and the <a href="#asynchronous-flag">asynchronous flag</a> is true</dt>
   <dd>
    <p><a href="#switch-headers-received">Switch to the HEADERS_RECEIVED state</a>.</p>

    <p><a href="#make-progress-notifications">Make progress notifications</a>.</p>
   </dd>

   <dt>Once the first byte (or more) of the
   <a href="#response-entity-body">response entity body</a> has been received, the
   <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a> is
   <i>success</i>, and the <a href="#asynchronous-flag">asynchronous flag</a> is true</dt>
   <dt>If there is no <a href="#response-entity-body">response entity body</a>, the
   <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a> is
   <i>success</i>, and the <a href="#asynchronous-flag">asynchronous flag</a> is true</dt>
   <dd><p><a href="#switch-loading">Switch to the LOADING state</a>.</dd>

   <dt>Once the whole <a href="#response-entity-body">response entity body</a> has been received
   and the <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a> is
   <i>success</i></dt>
   <dt>If there is no <a href="#response-entity-body">response entity body</a>, the
   <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a> is
   <i>success</i>, and the state is
   <a href="#dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING">LOADING</a></dt>
   <dt>If there is no <a href="#response-entity-body">response entity body</a>, the
   <a class="external" href="http://dev.w3.org/2006/waf/access-control/#cross-origin-request-status">cross-origin request status</a> is
   <i>success</i>, and the <a href="#asynchronous-flag">asynchronous flag</a> is false</dt>
   <dd><p><a href="#switch-done">Switch to the DONE state</a>.</dd>
  </dl>


  <hr>

  <p>When something is said to be a <dfn id="network-error">network error</dfn> run the
  <a href="#request-error">request error</a> steps for exception
  <code class="external" title="dom-DOMException-NETWORK_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-network_err">NETWORK_ERR</a></code> and event <code title="event-xhr-error"><a href="#event-xhr-error">error</a></code>.</p>

  <p>When something is said to be an <dfn id="abort-error">abort error</dfn> run the
  <a href="#request-error">request error</a> steps for exception
  <code class="external" title="dom-DOMException-ABORT_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-abort_err">ABORT_ERR</a></code> and event
  <code title="event-xhr-abort"><a href="#event-xhr-abort">abort</a></code>.</p>


  <p>When something is said to be an <dfn id="timeout-error">timeout error</dfn> run the
  <a href="#request-error">request error</a> steps for exception
  <code class="external" title="dom-DOMException-TIMEOUT_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-timeout_err">TIMEOUT_ERR</a></code> and event
  <code title="event-xhr-timeout"><a href="#event-xhr-timeout">timeout</a></code>.</p>


  <p>When something is said to be a <dfn id="request-error">request error</dfn> for
  exception <var>exception</var> and event <var>event</var> run these
  steps:</p>

  <ol>
   <li><p>The user agent should cancel any network
   activity for which the object is responsible.</li>

   <li><p>If there are any
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#concept-task" title="concept-task">tasks</a> from the
   object's <a href="#xmlhttprequest-task-source"><code>XMLHttpRequest</code> task source</a> in one of
   the <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#task-queue" title="task queue">task queues</a>,
   then remove them.

   <li><p>Set the the <a href="#error-flag">error flag</a> to true.</li>

   <li><p>Switch the state to <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a>.</li>

   <li><p>If the <a href="#asynchronous-flag">asynchronous flag</a> is false raise an
   <var>exception</var> exception and terminate the overall set of
   steps.</li>

   <li>
    <p><a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-event-fire" title="concept-event-fire">Fire an event</a> named <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code>.</p>

    <p class="note">At this point it is clear that the
    <a href="#asynchronous-flag">asynchronous flag</a> is true.</p>
   </li>


   <li>
    <p>If the <a href="#upload-complete-flag">upload complete flag</a> is false, follow these
    substeps:</p>

    <ol>
     <li><p>Set the <a href="#upload-complete-flag">upload complete flag</a> to true.</li>

     <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <var>event</var>
     on the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object.</li>

     <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named
     <code title="event-xhr-loadend"><a href="#event-xhr-loadend">loadend</a></code> on the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code>
     object.</li>
    </ol>
   </li>

   <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <var>event</var>.</li>

   <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-loadend"><a href="#event-xhr-loadend">loadend</a></code>.</li>

  </ol>



  <hr>

  <p>When it is said to
  <dfn id="switch-headers-received">switch to the HEADERS_RECEIVED state</dfn>
  run these steps:</p>

  <ol>
   <li><p>Switch the state to <a href="#dom-xmlhttprequest-headers_received" title="dom-XMLHttpRequest-HEADERS_RECEIVED">HEADERS_RECEIVED</a>.</li>

   <li><p><a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-event-fire" title="concept-event-fire">Fire an event</a> named <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code>.</li>
  </ol>

  <p>When it is said to
  <dfn id="switch-loading">switch to the LOADING state</dfn> run these
  steps:</p>

  <ol>
   <li><p>Switch the state to <a href="#dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING">LOADING</a>.</li>

   <li><p><a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-event-fire" title="concept-event-fire">Fire an event</a> named <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code>.</li>
  </ol>

  <p>When it is said to
  <dfn id="switch-done">switch to the DONE state</dfn> run these steps:</p>

  <ol>
   <li><p>If the <a href="#asynchronous-flag">asynchronous flag</a> is false update the
   <a href="#response-entity-body">response entity body</a>.</li>

   <li><p>Switch the state to <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a>.</li>

   <li><p><a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-event-fire" title="concept-event-fire">Fire an event</a> named <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code>.</li>


   <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-load"><a href="#event-xhr-load">load</a></code>.</li>

   <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-loadend"><a href="#event-xhr-loadend">loadend</a></code>.</li>

  </ol>


  <hr>

  <p>When it is said to <dfn id="make-progress-notifications">make progress notifications</dfn>, while the
  download is progressing, <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">queue a task</a> to
  <a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">fire a progress event</a> named <code title="event-xhr-progress"><a href="#event-xhr-progress">progress</a></code>
  about every 50ms or for every byte received, whichever is <em>least</em>
  frequent.</p>

  <hr>

  <p>When it is said to <dfn id="make-upload-progress-notifications">make upload progress notifications</dfn> run
  these steps:</p>

  <ul>
   <li><p>While the request entity body is being uploaded and the
   <a href="#upload-complete-flag">upload complete flag</a> is false,
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">queue a task</a> to
   <a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">fire a progress event</a> named <code title="event-xhr-progress"><a href="#event-xhr-progress">progress</a></code> at
   the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object about every 50ms or for
   every byte transmitted, whichever is <em>least</em> frequent.</li>

   <li>
    <p>If the <a href="#request-entity-body">request entity body</a> has been successfully
    uploaded and the <a href="#upload-complete-flag">upload complete flag</a> is still false,
    <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#queue-a-task">queue a task</a> to run these substeps:</p>

    <ol>
     <li><p>Set the <a href="#upload-complete-flag">upload complete flag</a> to true.</li>

     <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-load"><a href="#event-xhr-load">load</a></code>
     at the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object.</li>

     <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named
     <code title="event-xhr-loadend"><a href="#event-xhr-loadend">loadend</a></code> at the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code>
     object.</li>
    </ol>
   </li>
  </ul>

  <!-- XXX successfully uploaded? -->



  <h4 id="the-abort-method"><span class="secno">4.6.8 </span>The <code title="">abort()</code> method</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-abort"><a href="#dom-xmlhttprequest-abort">abort()</a></code></dt>
   <dd>Cancels any network activity.</dd>
  </dl>

  <p>When the
  <dfn id="dom-xmlhttprequest-abort" title="dom-XMLHttpRequest-abort"><code>abort()</code></dfn>
  method is invoked, the user agent must run these steps
  (unless otherwise noted). This algorithm can be
  <dfn id="terminate-abort" title="terminate abort()">terminated</dfn> by invoking the
  <code title="dom-XMLHttpRequest-open"><a href="#dom-xmlhttprequest-open">open()</a></code> method. When it is
  <a href="#terminate-abort" title="terminate abort()">terminated</a> the user agent
  must terminate the algorithm after finishing the step
  it is on.</p>

  <p class="note">The <code title="dom-XMLHttpRequest-abort"><a href="#dom-xmlhttprequest-abort">abort()</a></code>
  algorithm can only be terminated by invoking
  <code title="dom-XMLHttpRequest-open"><a href="#dom-xmlhttprequest-open">open()</a></code> from an event
  handler.</p>

  <ol>
   <li><p><a href="#terminate-send" title="terminate send()">Terminate the <code>send()</code> algorithm</a>.</li>

   <li><p>The user agent should cancel any network
   activity for which the object is responsible.</li>

   <li><p>If there are any
   <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#concept-task" title="concept-task">tasks</a> from the
   object's <a href="#xmlhttprequest-task-source"><code>XMLHttpRequest</code> task source</a> in one of
   the <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#task-queue" title="task queue">task queues</a>,
   then remove them.

   <li><p>Set the <a href="#error-flag">error flag</a> to true.</li>

   <li>
    <p>If the state is <a href="#dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT">UNSENT</a>,
    <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> with the
    <a href="#send-flag"><code>send()</code> flag</a> being false, or
    <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a> go to the next step.</p>

    <p>Otherwise run these substeps:</p>

    <ol>
     <li><p>Switch the state to <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a>.</li>

     <li><p>Set the <a href="#send-flag"><code>send()</code> flag</a> to false.</li>

     <li><p><a class="external" href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-event-fire" title="concept-event-fire">Fire an event</a> named <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code>.</li>


     <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-abort"><a href="#event-xhr-abort">abort</a></code>.</li>

     <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-loadend"><a href="#event-xhr-loadend">loadend</a></code>.</li>

     <li>
      <p>If the <a href="#upload-complete-flag">upload complete flag</a> is false run these
      substeps:</p>

      <ol>
       <li><p>Set the <a href="#upload-complete-flag">upload complete flag</a> to true.</li>

       <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-abort"><a href="#event-xhr-abort">abort</a></code>
       on the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object.</li>

       <li><p><a class="external" href="http://dev.w3.org/2006/webapi/progress/#concept-event-fire-progress" title="concept-event-fire-progress">Fire a progress event</a> named <code title="event-xhr-loadend"><a href="#event-xhr-loadend">loadend</a></code>
       on the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object.</li>
      </ol>
     </li>

    </ol>


   </li>

   <li>
    <p>Switch the state to <a href="#dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT">UNSENT</a>.</p>

    <p class="note">No <code title="event-xhr-readystatechange"><a href="#event-xhr-readystatechange">readystatechange</a></code> event is dispatched.</p>
   </li>
  </ol>



  <h3 id="response"><span class="secno">4.7 </span>Response</h3>

  <h4 id="the-status-attribute"><span class="secno">4.7.1 </span>The <code title="">status</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-status"><a href="#dom-xmlhttprequest-status">status</a></code></dt>
   <dd><p>Returns the HTTP status code.</dd>
  </dl>

  <p>The
  <dfn id="dom-xmlhttprequest-status" title="dom-XMLHttpRequest-status"><code>status</code></dfn>
  attribute must return the result of running these
  steps:</p>

  <ol>
   <li><p>If the state is <a href="#dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT">UNSENT</a> or
   <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> return 0 and terminate these
   steps.</li>

   <li><p>If the <a href="#error-flag">error flag</a> is true return 0 and terminate
   these steps.</li>

   <li><p>Return the HTTP status code.</li>
  </ol>


  <h4 id="the-statustext-attribute"><span class="secno">4.7.2 </span>The <code title="">statusText</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-statusText"><a href="#dom-xmlhttprequest-statustext">statusText</a></code></dt>
   <dd><p>Returns the HTTP status text.</dd>
  </dl>

  <p>The
  <dfn id="dom-xmlhttprequest-statustext" title="dom-XMLHttpRequest-statusText"><code>statusText</code></dfn>
  attribute must return the result of running these
  steps:</p>

  <ol>
   <li><p>If the state is <a href="#dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT">UNSENT</a> or
   <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> return the empty string and
   terminate these steps.</li>

   <li><p>If the <a href="#error-flag">error flag</a> is true return the empty string and
   terminate these steps.</li>

   <li><p>Return the HTTP status text.</li>
  </ol>


  <h4 id="the-getresponseheader-method"><span class="secno">4.7.3 </span>The <code title="">getResponseHeader()</code> method</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-getResponseHeader"><a href="#dom-xmlhttprequest-getresponseheader">getResponseHeader(<var title="">header</var>)</a></code></dt>
   <dd><p>Returns the header field value from the response of which the
   field name matches <var title="">header</var>, unless the field name is
   <code>Set-Cookie</code> or <code>Set-Cookie2</code>.</p>
  </dl>

  <p>When the
  <dfn id="dom-xmlhttprequest-getresponseheader" title="dom-XMLHttpRequest-getResponseHeader"><code>getResponseHeader(<var title="">header</var>)</code></dfn>
  is invoked, the user agent must run these steps:</p>

  <ol>
   <li><p>If the state is <a href="#dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT">UNSENT</a> or
   <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> return null and terminate these
   steps.</li>

   <li><p>If the <a href="#error-flag">error flag</a> is true return null
   and terminate these steps.</li>

   <li><p>If any code point in <var>header</var> is higher than
   U+00FF LATIN SMALL LETTER Y WITH DIAERESIS return null and terminate
   these steps.</li>

   <li><p>Let <var>header</var> be the result of
   <a href="#deflate-a-domstring-into-a-byte-sequence" title="deflate a DOMString into a byte sequence">deflating</a>
   <var>header</var>.</li> <!-- This sounds lame, but it works. -->

   <li><p>If <var>header</var> is a case-insensitive match for
   <code>Set-Cookie</code> or <code>Set-Cookie2</code> return null and
   terminate these steps.</li>

   <li><p>If <var>header</var> is a case-insensitive match for multiple HTTP
   response headers, return the
   <a href="#inflate-a-byte-sequence-into-a-domstring" title="inflate a byte sequence into a DOMString">inflated</a>
   values of these headers as a single concatenated string separated from
   each other by a U+002C COMMA U+0020 SPACE character pair and terminate
   these steps.</li>

   <li><p>If <var>header</var> is a case-insensitive match for a single HTTP
   response header, return the
   <a href="#inflate-a-byte-sequence-into-a-domstring" title="inflate a byte sequence into a DOMString">inflated</a>
   value of that header and terminate these steps.</li>

   <li><p>Return null.</li>
  </ol>


  <p class="note">The Cross-Origin Resource Sharing specification filters
  the headers that are exposed by
  <code title="dom-XMLHttpRequest-getResponseHeader"><a href="#dom-xmlhttprequest-getresponseheader">getResponseHeader()</a></code>
  for non <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin" title="same origin">same-origin</a>
  requests. <a href="#refsCORS">[CORS]</a>


  <div class="example">

   <p>For the following script:</p>

   <pre><code>var client = new XMLHttpRequest();
client.open("GET", "unicorns-are-teh-awesome.txt", true);
client.send();
client.onreadystatechange = function() {
  if(this.readyState == 2) {
    print(client.getResponseHeader("Content-Type"));
  }
}</code></pre>

   <p>The <code>print()</code> function will get to process something
   like:</p>

   <pre><code>text/plain; charset=UTF-8</code></pre>
  </div>


  <h4 id="the-getallresponseheaders-method"><span class="secno">4.7.4 </span>The <code title="">getAllResponseHeaders()</code> method</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-getAllResponseHeaders"><a href="#dom-xmlhttprequest-getallresponseheaders">getAllResponseHeaders()</a></code></dt>
   <dd><p>Returns all headers from the response, with the exception of those
   whose field name is <code>Set-Cookie</code> or
   <code>Set-Cookie2</code>.</dd>
  </dl>

  <p>When the
  <dfn id="dom-xmlhttprequest-getallresponseheaders" title="dom-XMLHttpRequest-getAllResponseHeaders"><code>getAllResponseHeaders()</code></dfn>
  method is invoked, the user agent must run these steps:</p>

  <ol>
   <li><p>If the state is <a href="#dom-xmlhttprequest-unsent" title="dom-XMLHttpRequest-UNSENT">UNSENT</a> or
   <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> return the empty string and
   terminate these steps.</li>

   <li><p>If the <a href="#error-flag">error flag</a> is true return the empty string and
   terminate these steps.</li>

   <li><p>Return all the HTTP headers, excluding headers that are a
   case-insensitive match for <code>Set-Cookie</code> or
   <code>Set-Cookie2</code>,
   <a href="#inflate-a-byte-sequence-into-a-domstring" title="inflate a byte sequence into a DOMString">inflated</a>,
   as a single string, with each header line
   separated by a U+000D CR U+000A LF pair, excluding the status line, and
   with each header name and header value separated by a
   U+003A COLON U+0020 SPACE pair.</li>
  </ol>


  <p class="note">The Cross-Origin Resource Sharing specification filters
  the headers that are exposed by
  <code title="dom-XMLHttpRequest-getAllResponseHeaders"><a href="#dom-xmlhttprequest-getallresponseheaders">getAllResponseHeaders()</a></code>
  for non <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#same-origin" title="same origin">same-origin</a>
  requests. <a href="#refsCORS">[CORS]</a>


  <div class="example">
   <p>For the following script:</p>

   <pre><code>var client = new XMLHttpRequest();
client.open("GET", "narwhals-too.txt", true);
client.send();
client.onreadystatechange = function() {
  if(this.readyState == 2) {
    print(this.getAllResponseHeaders());
  }
}</code></pre>

   <p>The <code>print()</code> function will get to process something
   like:</p>

   <pre><code>Date: Sun, 24 Oct 2004 04:58:38 GMT
Server: Apache/1.3.31 (Unix)
Keep-Alive: timeout=15, max=99
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: text/plain; charset=utf-8</code></pre>
  </div>



  <h4 id="response-entity-body-0"><span class="secno">4.7.5 </span>Response Entity Body</h4>

  <p>The <dfn id="response-mime-type">response MIME type</dfn> is the MIME
  type the <code>Content-Type</code> header contains without any
  parameters or null if the header could not be parsed properly or was
  omitted. The <dfn id="override-mime-type">override MIME type</dfn> is
  initially null and can get a value if <code title="dom-XMLHttpRequest-overrideMimeType"><a href="#dom-xmlhttprequest-overridemimetype">overrideMimeType()</a></code> is
  invoked. <dfn id="final-mime-type">Final MIME type</dfn> is the
  override MIME type unless that is null in which case it is the response
  MIME type.</p>

  <p>The <dfn id="response-charset">response charset</dfn> is the value of
  the <code>charset</code> parameter of the <code>Content-Type</code> header
  or null if there was no <code>charset</code> parameter or if
  the header could not be parsed properly or was omitted. The
  <dfn id="override-charset">override charset</dfn> is initially null and
  can get a value if <code title="dom-XMLHttpRequest-overrideMimeType"><a href="#dom-xmlhttprequest-overridemimetype">overrideMimeType()</a></code> is invoked.
  <dfn id="final-charset">Final charset</dfn> is the override charset unless
  that is null in which case it is the response charset.</p>



  <hr>

  <p>The <dfn id="response-entity-body">response entity body</dfn> is the
  fragment of the <a class="external" href="http://tools.ietf.org/html/rfc2616/#section-7.2">entity body</a> of the
  response received so far
  (<a href="#dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING">LOADING</a>) or the complete
  entity body of the response
  (<a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a>). If the response
  does not have an entity body the response entity body is null.</p>

  <p class="note">The <a href="#response-entity-body">response entity body</a> is updated as part
  of the <code title="dom-XMLHttpRequest-send"><a href="#dom-xmlhttprequest-send">send()</a></code> algorithm.</p>

  <hr>

  <p>The <dfn id="text-response-entity-body">text response entity body</dfn>
  is a <code>DOMString</code> representing the <a href="#response-entity-body">response entity
  body</a>. The text response entity body is the return value of the
  following algorithm:</p>

  <ol>
   <li><p>If the response entity body is null return the empty string and
   terminate these steps.</p>

   <li><p>Let <var>charset</var> be the <a href="#final-charset">final charset</a>.</li>

   <li><p>Let <var>mime</var> be the <a href="#final-mime-type">final MIME type</a>.</li>

   <li><p>If <var>charset</var> is null and <var>mime</var> is null,
   <code>text/xml</code>, <code>application/xml</code> or ends in
   <code title="">+xml</code> use the rules set forth in the XML
   specifications to determine the character encoding. Let
   <var>charset</var> be the determined character encoding.</li>

   <li><p>If <var>charset</var> is null and <var>mime</var> is
   <code>text/html</code> follow the rules set forth in the HTML
   specification to determine the character encoding. Let
   <var>charset</var> be the determined character encoding.
   <a href="#refsHTML">[HTML]</a>

   <li>
    <p>If <var>charset</var> is null then, for each of the rows in the
    following table, starting with the first one and going down, if the first
    bytes of <var>bytes</var> match the bytes given in the first column, then
    let <var>charset</var> be the encoding given in the cell in the second
    column of that row. If there is no match <var>charset</var> remains
    null.</p>

    <table>
     <thead>
      <tr>
       <th>Bytes in Hexadecimal
       <th>Description
     <tbody>
      <tr>
       <td>FE FF
       <td>UTF-16BE BOM
      <tr>
       <td>FF FE
       <td>UTF-16LE BOM
      <tr>
       <td>EF BB BF
       <td>UTF-8 BOM
    </table>
   </li>

   <li><p>If <var>charset</var> is null let <var>charset</var> be
   UTF-8.</li>

   <li><p>Return the result of decoding the response entity body using
   <var>charset</var>. Replace bytes or sequences of bytes that are not
   valid accordng to the <var>charset</var> with a single
   U+FFFD REPLACEMENT CHARACTER character. Remove one leading
   U+FEFF BYTE ORDER MARK character, if present.</li>
  </ol>

  <p class="note">Authors are strongly encouraged to always encode their
  resources using UTF-8.</p>

  <hr>

  <p>The <dfn id="document-response-entity-body">document response entity
  body</dfn> is either a <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code> representing the
  <a href="#response-entity-body">response entity body</a> or null. If it is a
  <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code> its <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/origin-0.html#origin">origin</a> is the
  <a href="#xmlhttprequest-origin"><code>XMLHttpRequest</code> origin</a>. If the
  <a href="#document-response-entity-body">document response entity body</a> has no value assigned to it let
  it be the return value of the following algorithm:</p>

  <ol>
   <li><p>If the <a href="#response-entity-body">response entity body</a> is null, return null and
   terminate these steps.</li>

   <li><p>If <a href="#final-mime-type">final MIME type</a> is not null,
   <code>text/html</code>, <code>text/xml</code>,
   <code>application/xml</code>, or does not end in
   <code title="">+xml</code>, return null and terminate these
   steps.</li>


   <li>
    <p>If <a href="#final-mime-type">final MIME type</a> is <code>text/html</code> let
    <var title="">document</var> be <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code> object that represents
    the <a href="#response-entity-body">response entity body</a> parsed following the rules set
    forth in the HTML specification for an HTML parser with scripting
    disabled. <a href="#refsHTML">[HTML]</a>
   </li>


   <li>
    <p>Otherwise, let <var title="">document</var> be a
    <code class="external"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#document">Document</a></code> object that represents the result of parsing the
    <a href="#response-entity-body">response entity body</a> into a document tree following the
    rules set forth in the XML specifications. If that fails
    (unsupported character encoding, namespace well-formedness error et
    cetera) return null and terminate these steps.
    <a href="#refsXML">[XML]</a> <a href="#refsXMLNS">[XMLNS]</a>

    <p class="note">Scripts in the resulting document tree will not be executed,
    resources referenced will not be loaded and no associated XSLT will be
    applied.</p> <!-- XXX more formally?! -->
   </li>

   <li><p>Return <var title="">document</var>.</li>
  </ol>


  <p>The
  <dfn id="blob-response-entity-body">blob response entity body</dfn> is a
  <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a></code> representing the <a href="#response-entity-body">response entity body</a>. If
  the <a href="#blob-response-entity-body">blob response entity body</a> has no value assigned to it let
  it be the return value of the following algorithm:</p>

  <ol>
   <li><p>If the <a href="#response-entity-body">response entity body</a> is null, return an empty
   <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a></code> object and terminate these steps.</li>

   <li><p>Return a <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a></code> object representing the
   <a href="#response-entity-body">response entity body</a>.</li>
  </ol>


  <p>The
  <dfn id="arraybuffer-response-entity-body">arraybuffer response entity body</dfn>
  is an <code class="external"><a href="http://www.khronos.org/registry/typedarray/specs/latest/#5">ArrayBuffer</a></code> representing
  the <a href="#response-entity-body">response entity body</a>. If the
  <a href="#arraybuffer-response-entity-body">arraybuffer response entity body</a> has no value assigned to it
  let it be the return value of the following algorithm:</p>

  <ol>
   <li><p>If the <a href="#response-entity-body">response entity body</a> is null, return an empty
   <code class="external"><a href="http://www.khronos.org/registry/typedarray/specs/latest/#5">ArrayBuffer</a></code> object and terminate
   these steps.</li>

   <li><p>Return an <code class="external"><a href="http://www.khronos.org/registry/typedarray/specs/latest/#5">ArrayBuffer</a></code>
   object representing the <a href="#response-entity-body">response entity body</a>.</li>
  </ol>



  <h4 id="the-overridemimetype-method"><span class="secno">4.7.6 </span>The <code title="">overrideMimeType()</code> method</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-overrideMimeType"><a href="#dom-xmlhttprequest-overridemimetype">overrideMimeType(<var title="">mime</var>)</a></code></dt>
   <dd>
    <p>Sets the <code>Content-Type</code> header for the response to
    <var title="">mime</var>.</p>

    <p>Throws an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception if the state is
    not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> or
    <a href="#dom-xmlhttprequest-headers_received" title="dom-XMLHttpRequest-HEADERS_RECEIVED">HEADERS_RECEIVED</a>.</p>

    <p>Throws a <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code> exception if
    <var title="">mime</var> is not a valid media type.</p>
   </dd>
  </dl>

  <p>When the
  <dfn id="dom-xmlhttprequest-overridemimetype" title="dom-XMLHttpRequest-overrideMimeType"><code>overrideMimeType(<var title="">mime</var>)</code></dfn>
  method is invoked, the user agent must run these
  steps:</p>

  <ol>
   <li><p>If the state is not
   <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> or
   <a href="#dom-xmlhttprequest-headers_received" title="dom-XMLHttpRequest-HEADERS_RECEIVED">HEADERS_RECEIVED</a>
   raise an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>If parsing <var title="">mime</var> analogously to the value of
   the <code>Content-Type</code> headers fails raise a
   <code class="external" title="dom-DOMException-SYNTAX_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-syntax_err">SYNTAX_ERR</a></code> exception and abort this algorithm.</li>

   <li><p>If a MIME type (without any parameters) is successfully parsed set
   <a href="#override-mime-type">override MIME type</a> to that MIME type.</li>

   <li><p>If a <code>charset</code> parameter is successfully parsed set
   <a href="#override-charset">override charset</a> to its value.</li>
  </ol>



  <h4 id="the-responsetype-attribute"><span class="secno">4.7.7 </span>The <code title="">responseType</code> attribute</h4>


  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> [ = <var title="">value</var> ]</dt>
   <dd>
    <p>Returns the response type.</p>
    <p>Can be set to change the response type. Values are:
    the empty string (default),
    "<code title="">arraybuffer</code>",
    "<code title="">blob</code>",
    "<code title="">document</code>", and
    "<code title="">text</code>".</p>
    <p>Throws an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception if the state is
    not <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> or
    <a href="#dom-xmlhttprequest-headers_received" title="dom-XMLHttpRequest-HEADERS_RECEIVED">HEADERS_RECEIVED</a>.</p>
   </dd>
  </dl>

  <p>On setting the
  <dfn id="dom-xmlhttprequest-responsetype" title="dom-XMLHttpRequest-responseType"><code>responseType</code></dfn>
  attribute these steps must be run:</p>

  <ol>
   <li><p>If the state is not
   <a href="#dom-xmlhttprequest-opened" title="dom-XMLHttpRequest-OPENED">OPENED</a> or
   <a href="#dom-xmlhttprequest-headers_received" title="dom-XMLHttpRequest-HEADERS_RECEIVED">HEADERS_RECEIVED</a>
   raise an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>

   <li><p>If the given value is not
    the empty string,
    "<code title="">arraybuffer</code>",
    "<code title="">blob</code>",
    "<code title="">document</code>", or
    "<code title="">text</code>"
    terminate these steps.</li>

   <li><p>Set the
   <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code>
   attribute's value to the given value.</li>
  </ol>

  <p>On getting the
  <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code>
  attribute it must return its value.</p>



  <h4 id="the-response-attribute"><span class="secno">4.7.8 </span>The <code title="">response</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-response"><a href="#dom-xmlhttprequest-response">response</a></code></dt>
   <dd><p>Returns the <a href="#response-entity-body">response entity body</a>.</dd>
  </dl>

  <p>The
  <dfn id="dom-xmlhttprequest-response" title="dom-XMLHttpRequest-response"><code>response</code></dfn>
  attribute must return the result of running these
  steps:</p>

  <dl class="switch">
   <dt>If <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code>
   is the empty string or "<code title="">text</code>"</dt>
   <dd>
    <ol>
     <li><p>If the state is not
     <a href="#dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING">LOADING</a> or
     <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a> return the empty
     string and terminate these steps.</li>

     <li><p>If the <a href="#error-flag">error flag</a> is true return the empty string
     and terminate these steps.</li>

     <li><p>Return the <a href="#text-response-entity-body">text response entity body</a>.</li>
    </ol>
   </dd>
   <dt>Otherwise</dt>
   <dd>
    <ol>
     <li><p>If the state is not
     <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a> return null and
     terminate these steps.</li>

     <li><p>If the <a href="#error-flag">error flag</a> is true return null and terminate
     these steps.</li>

     <li>
      <dl class="switch">
       <dt>If
       <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> is
       "<code title="">arraybuffer</code>"</dt>
       <dd><p>Return the
       <a href="#arraybuffer-response-entity-body">arraybuffer response entity body</a>.</dd>

       <dt>If
       <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> is
       "<code title="">blob</code>"</dt>
       <dd><p>Return the
       <a href="#blob-response-entity-body">blob response entity body</a>.</dd>

       <dt>If
       <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> is
       "<code title="">document</code>"</dt>
       <dd><p>Return the
       <a href="#document-response-entity-body">document response entity body</a>.</dd>
      </dl>
     </li>
    </ol>
   </dd>
  </dl>



  <h4 id="the-responsetext-attribute"><span class="secno">4.7.9 </span>The <code title="">responseText</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-responseText"><a href="#dom-xmlhttprequest-responsetext">responseText</a></code></dt>
   <dd>
    <p>Returns the <a href="#text-response-entity-body">text response entity body</a>.</p>

    <p>Throws an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception if
    <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> is not
    the empty string or "<code title="">text</code>".

   </dd>
  </dl>

  <p>The
  <dfn id="dom-xmlhttprequest-responsetext" title="dom-XMLHttpRequest-responseText"><code>responseText</code></dfn>
  attribute must return the result of running these
  steps:</p>

  <ol>

   <li><p>If
   <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> is not
   the empty string or "<code title="">text</code>" raise an
   <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>


   <li><p>If the state is not <a href="#dom-xmlhttprequest-loading" title="dom-XMLHttpRequest-LOADING">LOADING</a> or
   <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a> return the empty string and
   terminate these steps.</li>

   <li><p>If the <a href="#error-flag">error flag</a> is true return the empty string and
   terminate these steps.</li>

   <li><p>Return the <a href="#text-response-entity-body">text response entity body</a>.</li>
  </ol>


  <h4 id="the-responsexml-attribute"><span class="secno">4.7.10 </span>The <code title="">responseXML</code> attribute</h4>

  <dl class="domintro">
   <dt><var title="">client</var> . <code title="dom-XMLHttpRequest-responseXML"><a href="#dom-xmlhttprequest-responsexml">responseXML</a></code></dt>
   <dd>
    <p>Returns the <a href="#document-response-entity-body">document response entity body</a>.</p>

    <p>Throws an <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception if
    <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> is not
    the empty string or "<code title="">document</code>".

   </dd>
  </dl>

  <p>The
  <dfn id="dom-xmlhttprequest-responsexml" title="dom-XMLHttpRequest-responseXML"><code>responseXML</code></dfn>
  attribute must return the result of running these steps:</p>

  <ol>

   <li><p>If
   <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> is not
   the empty string or "<code title="">document</code>" raise an
   <code class="external" title="dom-DOMException-INVALID_STATE_ERR"><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#dom-domexception-invalid_state_err">INVALID_STATE_ERR</a></code> exception and terminate these
   steps.</li>


   <li><p>If the state is not <a href="#dom-xmlhttprequest-done" title="dom-XMLHttpRequest-DONE">DONE</a> return
   null and terminate these steps.</li>

   <li><p>If the <a href="#error-flag">error flag</a> is true return null and terminate
   these steps.</li>

   <li><p>Return the <a href="#document-response-entity-body">document response entity body</a>.</li>
  </ol>


  <p class="note">The
  <code title="dom-XMLHttpRequest-responseXML"><a href="#dom-xmlhttprequest-responsexml">responseXML</a></code> attribute
  has XML in its name for historical reasons. It also returns HTML resources
  as documents.</p>


  <h3 id="events"><span class="secno">4.8 </span>Events summary</h3>

  <p>The following events are dispatched on <code><a href="#xmlhttprequest">XMLHttpRequest</a></code>
  and/or <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> objects:</p>

  <table>
   <thead>
    <tr>
     <th>Event name</th>
     <th>Interface</th>
     <th>Dispatched when&hellip;</th>
    </tr>
   </thead>
   <tbody>
    <tr>
     <td><dfn id="event-xhr-readystatechange" title="event-xhr-readystatechange"><code>readystatechange</code></dfn></td>
     <td><code>Event</code></td>
     <td>The <code title="dom-XMLHttpRequest-readyState"><a href="#dom-xmlhttprequest-readystate">readyState</a></code>
     attribute changes at some seemingly arbitrary times for historical
     reasons.</td>
    </tr>
    <tr>
     <td><dfn id="event-xhr-loadstart" title="event-xhr-loadstart"><code>loadstart</code></dfn></td>
     <td><code>ProgressEvent</code></td>
     <td>When the request starts.</td>
    </tr>
    <tr>
     <td><dfn id="event-xhr-progress" title="event-xhr-progress"><code>progress</code></dfn></td>
     <td><code>ProgressEvent</code></td>
     <td>While sending and loading data.</td>
    </tr>
    <tr>
     <td><dfn id="event-xhr-abort" title="event-xhr-abort"><code>abort</code></dfn></td>
     <td><code>ProgressEvent</code></td>
     <td>When the request has been aborted. For instance, by invoking the
     <code title="dom-XMLHttpRequest-abort"><a href="#dom-xmlhttprequest-abort">abort()</a></code> method.</td>
    </tr>
    <tr>
     <td><dfn id="event-xhr-error" title="event-xhr-error"><code>error</code></dfn></td>
     <td><code>ProgressEvent</code></td>
     <td>When the request has failed.</td>
    </tr>
    <tr>
     <td><dfn id="event-xhr-load" title="event-xhr-load"><code>load</code></dfn></td>
     <td><code>ProgressEvent</code></td>
     <td>When the request has successfully completed.</td>
    </tr>
    <tr>
     <td><dfn id="event-xhr-timeout" title="event-xhr-timeout"><code>timeout</code></dfn></td>
     <td><code>ProgressEvent</code></td>
     <td>When the author specified timeout has passed before the request
     could complete.</td>
    </tr>
    <tr>
     <td><dfn id="event-xhr-loadend" title="event-xhr-loadend"><code>loadend</code></dfn></td>
     <td><code>ProgressEvent</code></td>
     <td>When the request has completed (either in success or failure).</td>
    </tr>
   </tbody>
  </table>



  <h2 id="the-formdata-interface"><span class="secno">5 </span>The <code title="">FormData</code> Interface</h2>

  <p>The <code><a href="#formdata">FormData</a></code> object represents an ordered collection of
  entries. Each entry has a name, a value, a type, and potentially a
  filename.</p>

  <pre class="idl">[<a href="#dom-formdata" title="dom-FormData">Constructor</a>,
 <a href="#dom-formdata-form" title="dom-FormData-form">Constructor</a>(<a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/forms.html#htmlformelement">HTMLFormElement</a> <var>form</var>)]
interface <dfn id="formdata">FormData</dfn> {
  void <a href="#dom-formdata-append" title="dom-FormData-append">append</a>(DOMString <var>name</var>, <a class="external" href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a> <var>value</var>);
  void <a href="#dom-formdata-append" title="dom-FormData-append">append</a>(DOMString <var>name</var>, DOMString <var>value</var>);
};</pre>


  <h3 id="formdata-constructors"><span class="secno">5.1 </span>Constructors</h3>

  <dl class="domintro">
   <dt><var title="">fd</var> = <code title="dom-FormData"><a href="#dom-formdata">FormData()</a></code></dt>
   <dd><p>Returns a new <code><a href="#formdata">FormData</a></code> object.</dd>
  </dl>

  <p>When the
  <dfn id="dom-formdata" title="dom-FormData"><code>FormData()</code></dfn>
  constructor is invoked a new <code><a href="#formdata">FormData</a></code> object
  must be returned.</p>

  <p>When the
  <dfn id="dom-formdata-form" title="dom-FormData-form"><code>FormData(<var>form</var>)</code></dfn>
  constructor is invoked (i.e. with a <var>form</var> argument) a new
  <code><a href="#formdata">FormData</a></code> object must be returned with as
  entries the result of
  <a class="external" href="http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#constructing-form-data-set">constructing the form data set</a> for
  <var>form</var>.</p>


  <h3 id="the-append-method"><span class="secno">5.2 </span>The <code title="">append()</code> method</h3>

  <dl class="domintro">
   <dt><var title="">fd</var> . <code title="dom-FormData-append"><a href="#dom-formdata-append">append(<var title="">name</var>, <var title="">value</var>)</a></code></dt>
   <dd><p>Appends a new name/value-pair to the <code><a href="#formdata">FormData</a></code>
   object.</dd>
  </dl>

  <p>When the
  <dfn id="dom-formdata-append" title="dom-FormData-append"><code>append(<var>name</var>, <var>value</var>)</code></dfn>
  method is invoked, the user agent must create a new
  entry with the following parameters set:</p>
  <ul>
   <li>Set its name to <var>name</var>.
   <li>Set its value to <var>value</var>.
   <li>Set its type to "text" if <var>value</var> is a string and "file" if
   it is a <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a></code>.
   <li>If type is "file" set filename to  "<code title="">blob</code>".
   <li>If type is "file" and <var>value</var> is a
   <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#file">File</a></code> whose
   <code class="external" title="dom-File-name"><a href="http://dev.w3.org/2006/webapi/FileAPI/#dfn-name">name</a></code> attribute
   is not the empty string, set filename to the attribute's value.
  </ul>
  <p>It then must append this entry to the end of the
  collection the <code><a href="#formdata">FormData</a></code> object represents.</p>



  <h2 class="no-num" id="differences">Differences from XMLHttpRequest</h2>

  <p>XMLHttpRequest Level 2 adds the following new features:</p>

  <ul>
   <li><p>The ability to make cross-origin requests.</li>

   <li><p>The ability to make anonymous requests &mdash;
   <code>Referer</code>, origin, and credentials are not part of the
   request.</li>

   <li><p>The ability to register for progress events. Both for downloads
   (put listeners on the <code><a href="#xmlhttprequest">XMLHttpRequest</a></code> object itself) and
   uploads (put listeners on the <code><a href="#xmlhttprequestupload">XMLHttpRequestUpload</a></code> object,
   returned by the <code title="dom-XMLHttpRequest-upload"><a href="#dom-xmlhttprequest-upload">upload</a></code>
   attribute).</li>

   <li><p>The ability to override the media type and character encoding of
   the response through the
   <code title="dom-XMLHttpRequest-overrideMimeType"><a href="#dom-xmlhttprequest-overridemimetype">overrideMimeType()</a></code>
   method.</li>

   <li><p>The ability to set a timeout for the request.</li>

   <li><p>The ability to transfer
   <code class="external"><a href="http://www.khronos.org/registry/typedarray/specs/latest/#5">ArrayBuffer</a></code>,
   <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#blob">Blob</a></code>,
   <code class="external"><a href="http://dev.w3.org/2006/webapi/FileAPI/#file">File</a></code> and <code><a href="#formdata">FormData</a></code>
   objects.</li>

   <li><p>The
   <code title="dom-XMLHttpRequest-responseType"><a href="#dom-xmlhttprequest-responsetype">responseType</a></code> and
   <code title="dom-XMLHttpRequest-response"><a href="#dom-xmlhttprequest-response">response</a></code>
   attributes.</li>
  </ul>



<h2 class="no-num" id="references">References</h2>
<h3 class="no-num" id="normative-references">Normative references</h3>
<div id="anolis-references-normative"><dl><dt id="refsCOOKIES">[COOKIES]
<dd><cite><a href="http://tools.ietf.org/html/rfc6265">HTTP State Management Mechanism</a></cite>, Adam Barth. IETF.

<dt id="refsCORS">[CORS]
<dd><cite><a href="http://dev.w3.org/2006/waf/access-control/">Cross-Origin Resource Sharing</a></cite>, Anne van Kesteren. W3C.

<dt id="refsDOMCORE">[DOMCORE]
<dd><cite><a href="http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html">DOM Core</a></cite>, Anne van Kesteren and Ms2ger. W3C.

<dt id="refsFILEAPI">[FILEAPI]
<dd><cite><a href="http://dev.w3.org/2006/webapi/FileAPI/">File API</a></cite>, Arun Ranganathan and Jonas Sicking. W3C.

<dt id="refsHTML">[HTML]
<dd><cite><a href="http://dev.w3.org/html5/spec/">HTML5</a></cite>, Ian Hickson. W3C.

<dt id="refsHTTP">[HTTP]
<dd><cite><a href="http://tools.ietf.org/html/rfc2616">Hypertext Transfer Protocol -- HTTP/1.1</a></cite>, Roy Fielding, J. Gettys, J. Mogul et al.. IETF.

<dt id="refsHTTPAUTH">[HTTPAUTH]
<dd><cite><a href="http://tools.ietf.org/html/rfc2617">HTTP Authentication: Basic and Digest Access Authentication</a></cite>, P. Hallam-Baker, J. Hostetler, S. Lawrence et al.. IETF.

<dt id="refsHTTPVERBSEC">[HTTPVERBSEC]
<dd><cite><a href="http://www.kb.cert.org/vuls/id/867593">Multiple vendors' web servers enable HTTP TRACE method by default</a></cite>. US-CERT.

<dd><cite><a href="http://www.kb.cert.org/vuls/id/288308">Microsoft Internet Information Server (IIS) vulnerable to cross-site scripting via HTTP TRACK method</a></cite>. US-CERT.

<dd><cite><a href="http://www.kb.cert.org/vuls/id/150227">HTTP proxy default configurations allow arbitrary TCP connections</a></cite>. US-CERT.

<dt id="refsPROGRESSEVENTS">[PROGRESSEVENTS]
<dd><cite><a href="http://dev.w3.org/2006/webapi/progress/">Progress Events</a></cite>, Anne van Kesteren. W3C.

<dt id="refsRFC2119">[RFC2119]
<dd><cite><a href="http://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a></cite>, Scott Bradner. IETF.

<dt id="refsTYPEDARRAY">[TYPEDARRAY]
<dd><cite><a href="http://www.khronos.org/registry/typedarray/specs/latest/">Typed Array</a></cite>, David Herman and Kenneth Russell. Khronos.

<dt id="refsWEBIDL">[WEBIDL]
<dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web IDL</a></cite>, Cameron McCormack. W3C.

<dt id="refsXML">[XML]
<dd><cite><a href="http://www.w3.org/TR/xml/">Extensible Markup Language</a></cite>, Tim Bray, Jean Paoli, C. M. Sperberg-McQueen et al.. W3C.

<dt id="refsXMLNS">[XMLNS]
<dd><cite><a href="http://www.w3.org/TR/xml-names/">Namespaces in XML</a></cite>, Tim Bray, Dave Hollander, Andrew Layman et al.. W3C.

</dl></div>

<h3 class="no-num" id="informative-references">Informative references</h3>
<div id="anolis-references-informative"><dl><dt id="refsECMASCRIPT">[ECMASCRIPT]
<dd><cite><a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm">ECMAScript Language Specification</a></cite>. ECMA.

</dl></div>



  <h2 class="no-num" id="acknowledgments">Acknowledgments</h2>

  <p>The editor would like to thank

  Addison Phillips,
  Ahmed Kamel,
  Alex Hopmann,
  Alex Vincent,
  Alexey Proskuryakov,
  Asbj&oslash;rn Ulsberg,
  Boris Zbarsky,
  Bj&ouml;rn H&ouml;hrmann,
  Cameron McCormack,
  Chris Marrin,
  Christophe Jolif,
  Charles McCathieNevile,
  Dan Winship,
  David Andersson,
  David Flanagan,
  David H&aring;s&auml;ther,
  David Levin,
  Dean Jackson,
  Denis Sureau,
  Doug Schepers,
  Douglas Livingstone,
  Elliotte Harold,
  Eric Lawrence,
  Eric Uhrhane,
  Erik Dahlstr&ouml;m,
  Geoffrey Sneddon,
  Gideon Cohn,
  Gorm Haug Eriksen,
  H&aring;kon Wium Lie,
  Hallvord R. M. Steen,
  Henri Sivonen,
  Huub Schaeks,
  Ian Davis,
  Ian Hickson,
  Ivan Herman,
  Jeff Walden,
  Jens Lindstr&ouml;m,
  Jim Deegan,
  Jim Ley,
  Joe Farro,
  Jonas Sicking,
  Julian Reschke,
  Karl Dubost,
  Lachlan Hunt,
  Maciej Stachowiak,
  Magnus Kristiansen,
  Marc Hadley,
  Marcos Caceres,
  Mark Baker,
  Mark Birbeck,
  Mark Nottingham,
  Mark S. Miller,
  Martin Hassman,
  Mohamed Zergaoui,
  Olli Pettay,
  Pawel Glowacki,
  Peter Michaux,
  Philip Taylor,
  Robin Berjon,
  Rune Halvorsen,
  Ruud Steltenpool,
  Sergiu Dumitriu,
  Simon Pieters,
  Stewart Brodie,
  Sunava Dutta,
  Thomas Roessler,
  Tom Magliery, and
  Zhenbin Xu

  for their contributions to this specification.</p>

  <p>Special thanks to the Microsoft employees who first implemented the
  <code title="">XMLHttpRequest</code> interface, which was first widely
  deployed by the Windows Internet Explorer browser.</p>

  <p>Special thanks also to the WHATWG for drafting an initial version of
  this specification in their Web Applications 1.0 document (now renamed to
  HTML). <a href="#refsHTML">[HTML]</a></p>

  <p>Thanks also to all those who have helped to improve this specification
  by sending suggestions and corrections. (Please, keep bugging us with your
  issues!)</p>