path: root/files/pl/web/api/xmlhttprequest/using_xmlhttprequest/index.html

---
title: Wykorzystanie XMLHttpRequest
slug: Web/API/XMLHttpRequest/Using_XMLHttpRequest
translation_of: Web/API/XMLHttpRequest/Using_XMLHttpRequest
original_slug: XMLHttpRequest/Using_XMLHttpRequest
---
<p><a href="/en-US/docs/DOM/XMLHttpRequest" title="XMLHttpRequest"><code>XMLHttpRequest</code></a> makes sending HTTP requests very easy.  You simply create an instance of the object, open a URL, and send the request.  The <a href="/en-US/docs/HTTP/HTTP_response_codes" title="HTTP response codes">HTTP status</a> of the result, as well as the result's contents, are available in the request object when the transaction is completed. This page outlines some of the common and even slightly obscure use cases for this powerful JavaScript object.</p>
<pre class="brush: js">function reqListener () {
  console.log(this.responseText);
}

var oReq = new XMLHttpRequest();
oReq.onload = reqListener;
oReq.open("get", "yourFile.txt", true);
oReq.send();</pre>
<h2 id="Types_of_requests">Types of requests</h2>
<p>A request made via XMLHttpRequest can fetch the data in one of two ways, asynchronously or synchronously. The type of request is dictated by the optional <code>async</code> argument (the third argument) that is set on the XMLHttpRequest <a href="/en-US/docs/DOM/XMLHttpRequest#open()" title="DOM/XMLHttpRequest#open()">open()</a> method. If this argument is <code>true</code> or not specified, the <code>XMLHttpRequest</code> is processed asynchronously, otherwise the process is handled synchronously. A detailed discussion and demonstrations of these two types of requests can be found on the <a href="/en-US/docs/DOM/XMLHttpRequest/Synchronous_and_Asynchronous_Requests" title="Synchronous and Asynchronous Requests">synchronous and asynchronous requests</a> page. In general, you should rarely if ever use synchronous requests.</p>
<div class="note">
 <strong>Note:</strong> Starting with Gecko 30.0 {{ geckoRelease("30.0") }}, synchronous requests on the main thread have been deprecated due to the negative effects to the user experience.</div>
<h2 id="Handling_responses">Handling responses</h2>
<p>There are several types of <a href="http://www.w3.org/TR/XMLHttpRequest2/#response" title="http://www.w3.org/TR/XMLHttpRequest2/#response">response attributes</a> defined by the W3C specification for XMLHttpRequest.  These tell the client making the XMLHttpRequest important information about the status of the response. Some<span style="line-height: 1.572;"> cases where dealing with non-text response types may involve some manipulation and analysis as outlined in the following sections.</span></p>
<h3 id="Analyzing_and_manipulating_the_responseXML_property">Analyzing and manipulating the <code>responseXML</code> property</h3>
<p>If you use <code>XMLHttpRequest </code>to get the content of a remote XML document, the <code>responseXML </code>property will be a DOM Object containing a parsed XML document, which can be hard to manipulate and analyze. There are four primary ways of analyzing this XML document:</p>
<ol>
 <li>Using <a href="/en-US/docs/XPath" title="XPath">XPath</a> to address (point to) parts of it.</li>
 <li>Using <a href="/en-US/docs/JXON" title="JXON">JXON</a> to convert it into a JavaScript Object tree.</li>
 <li>Manually <a href="/en-US/docs/Parsing_and_serializing_XML" title="Parsing_and_serializing_XML">Parsing and serializing XML</a> to strings or objects.</li>
 <li>Using <a href="/en-US/docs/XMLSerializer" title="XMLSerializer">XMLSerializer</a> to serialize <strong>DOM trees to strings or to files</strong>.</li>
 <li><a href="/en-US/docs/JavaScript/Reference/Global_Objects/RegExp" title="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/regexp">RegExp </a>can be used if you always know the content of the XML document beforehand. You might want to remove line breaks, if you use RegExp to scan with regard to linebreaks. However, this method is a "last resort" since if the XML code changes slightly, the method will likely fail.</li>
</ol>
<h3 id="Analyzing_and_manipulating_a_responseText_property_containing_an_HTML_document">Analyzing and manipulating a <code>responseText</code> property containing an HTML document</h3>
<div class="note">
 <strong>Note:</strong> The W3C <a href="http://dvcs.w3.org/hg/xhr/raw-file/tip/Overview.html">XMLHttpRequest</a> specification allows HTML parsing via the <code>XMLHttpRequest.responseXML</code> property. Read the article about <a href="/en-US/docs/HTML_in_XMLHttpRequest" title="HTML_in_XMLHttpRequest">HTML in XMLHttpRequest</a> for details.</div>
<p>If you use <code>XMLHttpRequest</code> to get the content of a remote HTML webpage, the <code>responseText</code> property is a string containing a "soup" of all the HTML tags, which can be hard to manipulate and analyze. There are three primary ways of analyzing this HTML soup string:</p>
<ol>
 <li>Use the <code>XMLHttpRequest.responseXML</code> property.</li>
 <li>Inject the content into the body of a <a href="/en-US/docs/Web/API/DocumentFragment">document fragment</a> via <code>fragment.body.innerHTML</code> and traverse the DOM of the fragment.</li>
 <li><a href="/en-US/docs/JavaScript/Reference/Global_Objects/RegExp" title="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/regexp">RegExp </a>can be used if you always know the content of the HTML <code>responseText </code>beforehand. You might want to remove line breaks, if you use RegExp to scan with regard to linebreaks. However, this method is a "last resort" since if the HTML code changes slightly, the method will likely fail.</li>
</ol>
<h2 id="Handling_binary_data">Handling binary data</h2>
<p>Although <code>XMLHttpRequest</code> is most commonly used to send and receive textual data, it can be used to send and receive binary content. There are several well tested methods for coercing the response of an XMLHttpRequest into sending binary data. These involve utilizing the <code>.overrideMimeType()</code> method on the XMLHttpRequest object and is a workable solution.</p>
<pre class="brush:js">var oReq = new XMLHttpRequest();
oReq.open("GET", url, true);
// retrieve data unprocessed as a binary string
oReq.overrideMimeType("text/plain; charset=x-user-defined");
/* ... */
</pre>
<p>The XMLHttpRequest Level 2 Specification adds new <a href="http://www.w3.org/TR/XMLHttpRequest2/#the-responsetype-attribute" title="http://www.w3.org/TR/XMLHttpRequest2/#the-responsetype-attribute">responseType attributes</a> which make sending and receiving binary data much easier.</p>
<pre class="brush:js">var oReq = new XMLHttpRequest();


oReq.onload = function(e) {
  var arraybuffer = oReq.response; // not responseText
  /* ... */
}
<span style="font-size: 1rem;">oReq.open("GET", url, true);
</span><span style="font-size: 1rem;"><span style="font-size: 1rem;">oReq.responseType = "arraybuffer";
</span>oReq.send();</span></pre>
<p>For more examples check out the <a href="/en-US/docs/DOM/XMLHttpRequest/Sending_and_Receiving_Binary_Data" title="DOM/XMLHttpRequest/Sending_and_Receiving_Binary_Data">Sending and Receiving Binary Data</a> page</p>
<h2 id="Monitoring_progress">Monitoring progress</h2>
<p><code>XMLHttpRequest</code> provides the ability to listen to various events that can occur while the request is being processed. This includes periodic progress notifications, error notifications, and so forth.</p>
<p>Support for DOM progress event monitoring of <code>XMLHttpRequest</code> transfers follows the Web API <a href="http://dev.w3.org/2006/webapi/progress/Progress.html" title="http://dev.w3.org/2006/webapi/progress/Progress.html">specification for progress events</a>: these events implement the {{domxref("ProgressEvent")}} interface.</p>
<pre class="brush:js">var oReq = new XMLHttpRequest();

oReq.addEventListener("progress", updateProgress, false);
oReq.addEventListener("load", transferComplete, false);
oReq.addEventListener("error", transferFailed, false);
oReq.addEventListener("abort", transferCanceled, false);

oReq.open();

// ...

// progress on transfers from the server to the client (downloads)
function updateProgress (oEvent) {
  if (oEvent.lengthComputable) {
    var percentComplete = oEvent.loaded / oEvent.total;
    // ...
  } else {
    // Unable to compute progress information since the total size is unknown
  }
}

function transferComplete(evt) {
  alert("The transfer is complete.");
}

function transferFailed(evt) {
  alert("An error occurred while transferring the file.");
}

function transferCanceled(evt) {
  alert("The transfer has been canceled by the user.");
}</pre>
<p>Lines 3-6 add event listeners for the various events that are sent while performing a data transfer using <code>XMLHttpRequest</code>.</p>
<div class="note">
 <strong>Note:</strong> You need to add the event listeners before calling <code>open()</code> on the request.  Otherwise the progress events will not fire.</div>
<p>The progress event handler, specified by the <code>updateProgress()</code> function in this example, receives the total number of bytes to transfer as well as the number of bytes transferred so far in the event's <code>total</code> and <code>loaded</code> fields.  However, if the <code>lengthComputable</code> field is false, the total length is not known and will be zero.</p>
<p>Progress events exist for both download and upload transfers. The download events are fired on the <code>XMLHttpRequest</code> object itself, as shown in the above sample. The upload events are fired on the <code>XMLHttpRequest.upload</code> object, as shown below:</p>
<pre class="brush:js">var oReq = new XMLHttpRequest();

oReq.upload.addEventListener("progress", updateProgress, false);
oReq.upload.addEventListener("load", transferComplete, false);
oReq.upload.addEventListener("error", transferFailed, false);
oReq.upload.addEventListener("abort", transferCanceled, false);

oReq.open();
</pre>
<div class="note">
 <strong>Note:</strong> Progress events are not available for the <code>file:</code> protocol.</div>
<div class="note">
 <strong>Note</strong>: Currently there are open bugs for the progress event that are still affecting version 25 of Firefox on <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=908375">OS X</a> and <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=786953">Linux</a>.</div>
<div class="note">
 <p><strong>Note:</strong> Starting in {{Gecko("9.0")}}, progress events can now be relied upon to come in for every chunk of data received, including the last chunk in cases in which the last packet is received and the connection closed before the progress event is fired. In this case, the progress event is automatically fired when the load event occurs for that packet. This lets you now reliably monitor progress by only watching the "progress" event.</p>
</div>
<div class="note">
 <p><strong>Note:</strong> As of {{Gecko("12.0")}}, if your progress event is called with a <code>responseType</code> of "moz-blob", the value of response is a {{domxref("Blob")}} containing the data received so far.</p>
</div>
<p>One can also detect all three load-ending conditions (<code>abort</code>, <code>load</code>, or <code>error</code>) using the <code>loadend</code> event:</p>
<pre class="brush:js">req.addEventListener("loadend", loadEnd, false);

function loadEnd(e) {
  alert("The transfer finished (although we don't know if it succeeded or not).");
}
</pre>
<p>Note that there's no way to be certain from the information received by the <code>loadend</code> event as to which condition caused the operation to terminate; however, you can use this to handle tasks that need to be performed in all end-of-transfer scenarios.</p>
<h2 id="Submitting_forms_and_uploading_files">Submitting forms and uploading files</h2>
<p>Instances of <code>XMLHttpRequest</code> can be used to submit forms in two ways:</p>
<ul>
 <li>using nothing but AJAX</li>
 <li>using the <a href="/en-US/docs/DOM/XMLHttpRequest/FormData" title="DOM/XMLHttpRequest/FormData"><code>FormData</code></a> API</li>
</ul>
<p>The <strong>second way</strong> (using the <a href="/en-US/docs/DOM/XMLHttpRequest/FormData" title="DOM/XMLHttpRequest/FormData"><code>FormData</code></a> API) is the simplest and the fastest, but has the disadvantage that the data collected can not be <a href="/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify" title="/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify">stringified</a>.<br>
 The <strong>first way</strong> is instead the most complex but also lends itself to be the most flexible and powerful.</p>
<h3 id="Using_nothing_but_XMLHttpRequest">Using nothing but <code>XMLHttpRequest</code></h3>
<p>Submitting forms without the <a href="/en-US/docs/DOM/XMLHttpRequest/FormData" title="DOM/XMLHttpRequest/FormData"><code>FormData</code></a> API does not require other APIs, except that, only <strong>if you want to upload one or more files</strong>, the <a href="/en-US/docs/DOM/FileReader" title="/en-US/docs/DOM/FileReader"><code>FileReader</code></a> API.</p>
<h4 id="A_brief_introduction_to_the_submit_methods">A brief introduction to the submit methods</h4>
<p>An html {{ HTMLElement("form") }} can be sent in four ways:</p>
<ul>
 <li>using the <code>POST</code> method and setting the <code>enctype</code> attribute to <code>application/x-www-form-urlencoded</code> (default);</li>
 <li>using the <code>POST</code> method and setting the <code>enctype</code> attribute to <code>text/plain</code>;</li>
 <li>using the <code>POST</code> method and setting the <code>enctype</code> attribute to <code>multipart/form-data</code>;</li>
 <li>using the <code>GET</code> method (in this case the <code>enctype</code> attribute will be ignored).</li>
</ul>
<p>Now, consider to submit a form containing only two fields, named <code>foo</code> and <code>baz</code>. If you are using the <code>POST</code> method, the server will receive a string similar to one of the following three ones depending on the encoding type you are using:</p>
<ul>
 <li>
  <p>Method: <code>POST</code>; Encoding type: <code>application/x-www-form-urlencoded</code> (default):</p>
  <pre>Content-Type: application/x-www-form-urlencoded

foo=bar&amp;baz=The+first+line.&amp;#37;0D%0AThe+second+line.%0D%0A</pre>
 </li>
 <li>
  <p>Method: <code>POST</code>; Encoding type: <code>text/plain</code>:</p>
  <pre>Content-Type: text/plain

foo=bar
baz=The first line.
The second line.</pre>
 </li>
 <li>
  <p>Method: <code>POST</code>; Encoding type: <code>multipart/form-data</code>:</p>
  <pre style="height: 100px; overflow: auto;">Content-Type: multipart/form-data; boundary=---------------------------314911788813839

-----------------------------314911788813839
Content-Disposition: form-data; name="foo"

bar
-----------------------------314911788813839
Content-Disposition: form-data; name="baz"

The first line.
The second line.

-----------------------------314911788813839--</pre>
 </li>
</ul>
<p>Instead, if you are using the <code>GET</code> method, a string like the following will be simply added to the URL:</p>
<pre>?foo=bar&amp;baz=The%20first%20line.%0AThe%20second%20line.</pre>
<h4 id="A_little_vanilla_framework">A little vanilla framework</h4>
<p>All these things are done automatically by the web browser whenever you submit a {{ HTMLElement("form") }}. But if you want to do the same things using JavaScript you have to instruct the interpreter about <em>all</em> things. So, how to send forms in <em>pure</em> AJAX is too complex to be explained in detail here. For this reason we posted here <strong>a complete (but still didactic) framework</strong>, which is able to use all the four ways of <em>submit</em> and, also, to <strong>upload files</strong>:</p>
<div style="height: 400px; margin-bottom: 12px; overflow: auto;">
 <pre class="brush: html">&lt;!doctype html&gt;
&lt;html&gt;
&lt;head&gt;
&lt;meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /&gt;
&lt;title&gt;Sending forms with pure AJAX &amp;ndash; MDN&lt;/title&gt;
&lt;script type="text/javascript"&gt;

"use strict";

/*\
|*|
|*|  :: XMLHttpRequest.prototype.sendAsBinary() Polyfill ::
|*|
|*|  https://developer.mozilla.org/en-US/docs/DOM/XMLHttpRequest#sendAsBinary()
\*/

if (!XMLHttpRequest.prototype.sendAsBinary) {
  XMLHttpRequest.prototype.sendAsBinary = function(sData) {
    var nBytes = sData.length, ui8Data = new Uint8Array(nBytes);
    for (var nIdx = 0; nIdx &lt; nBytes; nIdx++) {
      ui8Data[nIdx] = sData.charCodeAt(nIdx) &amp; 0xff;
    }
    /* send as ArrayBufferView...: */
    this.send(ui8Data);
    /* ...or as ArrayBuffer (legacy)...: this.send(ui8Data.buffer); */
  };
}

/*\
|*|
|*|  :: AJAX Form Submit Framework ::
|*|
|*|  https://developer.mozilla.org/en-US/docs/DOM/XMLHttpRequest/Using_XMLHttpRequest
|*|
|*|  This framework is released under the GNU Public License, version 3 or later.
|*|  http://www.gnu.org/licenses/gpl-3.0-standalone.html
|*|
|*|  Syntax:
|*|
|*|   AJAXSubmit(HTMLFormElement);
\*/

var AJAXSubmit = (function () {

  function ajaxSuccess () {
    /* console.log("AJAXSubmit - Success!"); */
    alert(this.responseText);
    /* you can get the serialized data through the "submittedData" custom property: */
    /* alert(JSON.stringify(this.submittedData)); */
  }

  function submitData (oData) {
    /* the AJAX request... */
    var oAjaxReq = new XMLHttpRequest();
    oAjaxReq.submittedData = oData;
    oAjaxReq.onload = ajaxSuccess;
    if (oData.technique === 0) {
      /* method is GET */
      oAjaxReq.open("get", oData.receiver.replace(/(?:\?.*)?$/, oData.segments.length &gt; 0 ? "?" + oData.segments.join("&amp;") : ""), true);
      oAjaxReq.send(null);
    } else {
      /* method is POST */
      oAjaxReq.open("post", oData.receiver, true);
      if (oData.technique === 3) {
        /* enctype is multipart/form-data */
        var sBoundary = "---------------------------" + Date.now().toString(16);
        oAjaxReq.setRequestHeader("Content-Type", "multipart\/form-data; boundary=" + sBoundary);
        oAjaxReq.sendAsBinary("--" + sBoundary + "\r\n" + oData.segments.join("--" + sBoundary + "\r\n") + "--" + sBoundary + "--\r\n");
      } else {
        /* enctype is application/x-www-form-urlencoded or text/plain */
        oAjaxReq.setRequestHeader("Content-Type", oData.contentType);
        oAjaxReq.send(oData.segments.join(oData.technique === 2 ? "\r\n" : "&amp;"));
      }
    }
  }

  function processStatus (oData) {
    if (oData.status &gt; 0) { return; }
    /* the form is now totally serialized! do something before sending it to the server... */
    /* doSomething(oData); */
    /* console.log("AJAXSubmit - The form is now serialized. Submitting..."); */
    submitData (oData);
  }

  function pushSegment (oFREvt) {
    this.owner.segments[this.segmentIdx] += oFREvt.target.result + "\r\n";
    this.owner.status--;
    processStatus(this.owner);
  }

  function plainEscape (sText) {
    /* how should I treat a text/plain form encoding? what characters are not allowed? this is what I suppose...: */
    /* "4\3\7 - Einstein said E=mc2" ----&gt; "4\\3\\7\ -\ Einstein\ said\ E\=mc2" */
    return sText.replace(/[\s\=\\]/g, "\\$&amp;");
  }

  function SubmitRequest (oTarget) {
    var nFile, sFieldType, oField, oSegmReq, oFile, bIsPost = oTarget.method.toLowerCase() === "post";
    /* console.log("AJAXSubmit - Serializing form..."); */
    this.contentType = bIsPost &amp;&amp; oTarget.enctype ? oTarget.enctype : "application\/x-www-form-urlencoded";
    this.technique = bIsPost ? this.contentType === "multipart\/form-data" ? 3 : this.contentType === "text\/plain" ? 2 : 1 : 0;
    this.receiver = oTarget.action;
    this.status = 0;
    this.segments = [];
    var fFilter = this.technique === 2 ? plainEscape : escape;
    for (var nItem = 0; nItem &lt; oTarget.elements.length; nItem++) {
      oField = oTarget.elements[nItem];
      if (!oField.hasAttribute("name")) { continue; }
      sFieldType = oField.nodeName.toUpperCase() === "INPUT" ? oField.getAttribute("type").toUpperCase() : "TEXT";
      if (sFieldType === "FILE" &amp;&amp; oField.files.length &gt; 0) {
        if (this.technique === 3) {
          /* enctype is multipart/form-data */
          for (nFile = 0; nFile &lt; oField.files.length; nFile++) {
            oFile = oField.files[nFile];
            oSegmReq = new FileReader();
            /* (custom properties:) */
            oSegmReq.segmentIdx = this.segments.length;
            oSegmReq.owner = this;
            /* (end of custom properties) */
            oSegmReq.onload = pushSegment;
            this.segments.push("Content-Disposition: form-data; name=\"" + oField.name + "\"; filename=\""+ oFile.name + "\"\r\nContent-Type: " + oFile.type + "\r\n\r\n");
            this.status++;
            oSegmReq.readAsBinaryString(oFile);
          }
        } else {
          /* enctype is application/x-www-form-urlencoded or text/plain or method is GET: files will not be sent! */
          for (nFile = 0; nFile &lt; oField.files.length; this.segments.push(fFilter(oField.name) + "=" + fFilter(oField.files[nFile++].name)));
        }
      } else if ((sFieldType !== "RADIO" &amp;&amp; sFieldType !== "CHECKBOX") || oField.checked) {
        /* field type is not FILE or is FILE but is empty */
        this.segments.push(
          this.technique === 3 ? /* enctype is multipart/form-data */
            "Content-Disposition: form-data; name=\"" + oField.name + "\"\r\n\r\n" + oField.value + "\r\n"
          : /* enctype is application/x-www-form-urlencoded or text/plain or method is GET */
            fFilter(oField.name) + "=" + fFilter(oField.value)
        );
      }
    }
    processStatus(this);
  }

  return function (oFormElement) {
    if (!oFormElement.action) { return; }
    new SubmitRequest(oFormElement);
  };

})();

&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;

&lt;h1&gt;Sending forms with pure AJAX&lt;/h1&gt;

&lt;h2&gt;Using the GET method&lt;/h2&gt;

&lt;form action="register.php" method="get" onsubmit="AJAXSubmit(this); return false;"&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Registration example&lt;/legend&gt;
    &lt;p&gt;
      First name: &lt;input type="text" name="firstname" /&gt;&lt;br /&gt;
      Last name: &lt;input type="text" name="lastname" /&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input type="submit" value="Submit" /&gt;
    &lt;/p&gt;
  &lt;/fieldset&gt;
&lt;/form&gt;

&lt;h2&gt;Using the POST method&lt;/h2&gt;
&lt;h3&gt;Enctype: application/x-www-form-urlencoded (default)&lt;/h3&gt;

&lt;form action="register.php" method="post" onsubmit="AJAXSubmit(this); return false;"&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Registration example&lt;/legend&gt;
    &lt;p&gt;
      First name: &lt;input type="text" name="firstname" /&gt;&lt;br /&gt;
      Last name: &lt;input type="text" name="lastname" /&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input type="submit" value="Submit" /&gt;
    &lt;/p&gt;
  &lt;/fieldset&gt;
&lt;/form&gt;

&lt;h3&gt;Enctype: text/plain&lt;/h3&gt;

&lt;form action="register.php" method="post" enctype="text/plain" onsubmit="AJAXSubmit(this); return false;"&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Registration example&lt;/legend&gt;
    &lt;p&gt;
      Your name: &lt;input type="text" name="user" /&gt;
    &lt;/p&gt;
    &lt;p&gt;
      Your message:&lt;br /&gt;
      &lt;textarea name="message" cols="40" rows="8"&gt;&lt;/textarea&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input type="submit" value="Submit" /&gt;
    &lt;/p&gt;
  &lt;/fieldset&gt;
&lt;/form&gt;

&lt;h3&gt;Enctype: multipart/form-data&lt;/h3&gt;

&lt;form action="register.php" method="post" enctype="multipart/form-data" onsubmit="AJAXSubmit(this); return false;"&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Upload example&lt;/legend&gt;
    &lt;p&gt;
      First name: &lt;input type="text" name="firstname" /&gt;&lt;br /&gt;
      Last name: &lt;input type="text" name="lastname" /&gt;&lt;br /&gt;
      Sex:
      &lt;input id="sex_male" type="radio" name="sex" value="male" /&gt; &lt;label for="sex_male"&gt;Male&lt;/label&gt;
      &lt;input id="sex_female" type="radio" name="sex" value="female" /&gt; &lt;label for="sex_female"&gt;Female&lt;/label&gt;&lt;br /&gt;
      Password: &lt;input type="password" name="secret" /&gt;&lt;br /&gt;
      What do you prefer:
      &lt;select name="image_type"&gt;
        &lt;option&gt;Books&lt;/option&gt;
        &lt;option&gt;Cinema&lt;/option&gt;
        &lt;option&gt;TV&lt;/option&gt;
      &lt;/select&gt;
    &lt;/p&gt;
    &lt;p&gt;
      Post your photos:
      &lt;input type="file" multiple name="photos[]"&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input id="vehicle_bike" type="checkbox" name="vehicle[]" value="Bike" /&gt; &lt;label for="vehicle_bike"&gt;I have a bike&lt;/label&gt;&lt;br /&gt;
      &lt;input id="vehicle_car" type="checkbox" name="vehicle[]" value="Car" /&gt; &lt;label for="vehicle_car"&gt;I have a car&lt;/label&gt;
    &lt;/p&gt;
    &lt;p&gt;
      Describe yourself:&lt;br /&gt;
      &lt;textarea name="description" cols="50" rows="8"&gt;&lt;/textarea&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input type="submit" value="Submit" /&gt;
    &lt;/p&gt;
  &lt;/fieldset&gt;
&lt;/form&gt;

&lt;/body&gt;
&lt;/html&gt;</pre>
</div>
<p>To test it, create a<span class="long_text short_text" id="result_box" lang="en"><span class="hps"> </span></span>page named <strong>register.php</strong> (which is the <code>action</code> attribute of these sample forms) and just put the following <em><span class="long_text short_text" id="result_box" lang="en"><span class="hps">minimalistic </span></span></em>content:</p>
<pre class="brush: php">&lt;?php
/* register.php */

header("Content-type: text/plain");

/*
NOTE: You should never use `print_r()` in production scripts, or
otherwise output client-submitted data without sanitizing it first.
Failing to sanitize can lead to cross-site scripting vulnerabilities.
*/

echo ":: data received via GET ::\n\n";
print_r($_GET);

echo "\n\n:: Data received via POST ::\n\n";
print_r($_POST);

echo "\n\n:: Data received as \"raw\" (text/plain encoding) ::\n\n";
if (isset($HTTP_RAW_POST_DATA)) { echo $HTTP_RAW_POST_DATA; }

echo "\n\n:: Files received ::\n\n";
print_r($_FILES);

</pre>
<p>The syntax of this script is the following:</p>
<pre class="syntaxbox">AJAXSubmit(myForm);</pre>
<div class="note">
 <strong>Note:</strong> This framework uses the <a href="/en-US/docs/DOM/FileReader" title="/en-US/docs/DOM/FileReader"><code>FileReader</code></a> API to transmit file uploads. This is a recent API and is not implemented in IE9 or below. For this reason, the AJAX-only upload is considered <strong>an experimental technique</strong>. If you do not need to upload binary files, this framework work fine in most browsers.</div>
<div class="note">
 <strong>Note:</strong> The best way to send binary content is via <a href="/en-US/docs/JavaScript/Typed_arrays/ArrayBuffer" title="/en-US/docs/JavaScript/Typed_arrays/ArrayBuffer">ArrayBuffers</a> or <a href="/en-US/docs/DOM/Blob" title="/en-US/docs/DOM/Blob">Blobs</a> in conjuncton with the <a href="/en-US/docs/DOM/XMLHttpRequest#send%28%29" title="/en-US/docs/DOM/XMLHttpRequest#send()"><code>send()</code></a> method and possibly the <a href="/en-US/docs/DOM/FileReader#readAsArrayBuffer()" title="/en-US/docs/DOM/FileReader#readAsArrayBuffer()"><code>readAsArrayBuffer()</code></a> method of the <a href="/en-US/docs/DOM/FileReader" title="/en-US/docs/DOM/FileReader"><code>FileReader</code></a> API. But, since the aim of this script is to work with a <a href="/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify" title="/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify">stringifiable</a> raw data, we used the <a href="/en-US/docs/DOM/XMLHttpRequest#sendAsBinary%28%29" title="/en-US/docs/DOM/XMLHttpRequest#sendAsBinary()"><code>sendAsBinary()</code></a> method in conjunction with the <a href="/en-US/docs/DOM/FileReader#readAsBinaryString%28%29" title="/en-US/docs/DOM/FileReader#readAsBinaryString()"><code>readAsBinaryString()</code></a> method of the <a href="/en-US/docs/DOM/FileReader" title="/en-US/docs/DOM/FileReader"><code>FileReader</code></a> API. As such, the above script makes sense only when you are dealing with small files. If you do not intend to upload binary content, consider instead using the <a href="/en-US/docs/DOM/XMLHttpRequest/FormData" title="DOM/XMLHttpRequest/FormData"><code>FormData</code></a> API.</div>
<div class="note">
 <strong>Note:</strong> The non-standard <code>sendAsBinary </code>method is considered deprecated as of Gecko 31 {{ geckoRelease(31) }} and will be removed soon. The standard <code>send(Blob data)</code> method can be used instead.</div>
<h3 id="Using_FormData_objects">Using FormData objects</h3>
<p>The <a href="/en-US/docs/DOM/XMLHttpRequest/FormData" title="DOM/XMLHttpRequest/FormData"><code>FormData</code></a> constructor lets you compile a set of key/value pairs to send using <code>XMLHttpRequest</code>. Its primarily intended for use in sending form data, but can be used independently from forms in order to transmit keyed data. The transmitted data is in the same format that the form's <code>submit()</code> method would use to send the data if the form's encoding type were set to "multipart/form-data". FormData objects can be utilized in a number of ways with an XMLHttpRequest. For examples and explanations of how one can utilize FormData with XMLHttpRequests see the <a href="/en-US/docs/DOM/XMLHttpRequest/FormData/Using_FormData_Objects" title="Using FormData Objects">Using FormData Objects</a> page. For didactic purpose only we post here <strong>a <em>translation</em> of <a href="#A_little_vanilla_framework" title="#A_little_vanilla_framework">the previous example</a> transformed so as to make use of the <code>FormData</code> API</strong>. Note the brevity of the code:</p>
<div style="height: 400px; margin-bottom: 12px; overflow: auto;">
 <pre class="brush: html">&lt;!doctype html&gt;
&lt;html&gt;
&lt;head&gt;
&lt;meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /&gt;
&lt;title&gt;Sending forms with FormData &amp;ndash; MDN&lt;/title&gt;
&lt;script type="text/javascript"&gt;
"use strict";

function ajaxSuccess () {
  alert(this.responseText);
}

function AJAXSubmit (oFormElement) {
  if (!oFormElement.action) { return; }
  var oReq = new XMLHttpRequest();
  oReq.onload = ajaxSuccess;
  if (oFormElement.method.toLowerCase() === "post") {
    oReq.open("post", oFormElement.action, true);
    oReq.send(new FormData(oFormElement));
  } else {
    var oField, sFieldType, nFile, sSearch = "";
    for (var nItem = 0; nItem &lt; oFormElement.elements.length; nItem++) {
      oField = oFormElement.elements[nItem];
      if (!oField.hasAttribute("name")) { continue; }
      sFieldType = oField.nodeName.toUpperCase() === "INPUT" ? oField.getAttribute("type").toUpperCase() : "TEXT";
      if (sFieldType === "FILE") {
        for (nFile = 0; nFile &lt; oField.files.length; sSearch += "&amp;" + escape(oField.name) + "=" + escape(oField.files[nFile++].name));
      } else if ((sFieldType !== "RADIO" &amp;&amp; sFieldType !== "CHECKBOX") || oField.checked) {
        sSearch += "&amp;" + escape(oField.name) + "=" + escape(oField.value);
      }
    }
    oReq.open("get", oFormElement.action.replace(/(?:\?.*)?$/, sSearch.replace(/^&amp;/, "?")), true);
    oReq.send(null);
  }
}
&lt;/script&gt;
&lt;/head&gt;
&lt;body&gt;

&lt;h1&gt;Sending forms with FormData&lt;/h1&gt;

&lt;h2&gt;Using the GET method&lt;/h2&gt;

&lt;form action="register.php" method="get" onsubmit="AJAXSubmit(this); return false;"&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Registration example&lt;/legend&gt;
    &lt;p&gt;
      First name: &lt;input type="text" name="firstname" /&gt;&lt;br /&gt;
      Last name: &lt;input type="text" name="lastname" /&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input type="submit" value="Submit" /&gt;
    &lt;/p&gt;
  &lt;/fieldset&gt;
&lt;/form&gt;

&lt;h2&gt;Using the POST method&lt;/h2&gt;
&lt;h3&gt;Enctype: application/x-www-form-urlencoded (default)&lt;/h3&gt;

&lt;form action="register.php" method="post" onsubmit="AJAXSubmit(this); return false;"&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Registration example&lt;/legend&gt;
    &lt;p&gt;
      First name: &lt;input type="text" name="firstname" /&gt;&lt;br /&gt;
      Last name: &lt;input type="text" name="lastname" /&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input type="submit" value="Submit" /&gt;
    &lt;/p&gt;
  &lt;/fieldset&gt;
&lt;/form&gt;

&lt;h3&gt;Enctype: text/plain&lt;/h3&gt;

&lt;p&gt;The text/plain encoding is not supported by the FormData API.&lt;/p&gt;

&lt;h3&gt;Enctype: multipart/form-data&lt;/h3&gt;

&lt;form action="register.php" method="post" enctype="multipart/form-data" onsubmit="AJAXSubmit(this); return false;"&gt;
  &lt;fieldset&gt;
    &lt;legend&gt;Upload example&lt;/legend&gt;
    &lt;p&gt;
      First name: &lt;input type="text" name="firstname" /&gt;&lt;br /&gt;
      Last name: &lt;input type="text" name="lastname" /&gt;&lt;br /&gt;
      Sex:
      &lt;input id="sex_male" type="radio" name="sex" value="male" /&gt; &lt;label for="sex_male"&gt;Male&lt;/label&gt;
      &lt;input id="sex_female" type="radio" name="sex" value="female" /&gt; &lt;label for="sex_female"&gt;Female&lt;/label&gt;&lt;br /&gt;
      Password: &lt;input type="password" name="secret" /&gt;&lt;br /&gt;
      What do you prefer:
      &lt;select name="image_type"&gt;
        &lt;option&gt;Books&lt;/option&gt;
        &lt;option&gt;Cinema&lt;/option&gt;
        &lt;option&gt;TV&lt;/option&gt;
      &lt;/select&gt;
    &lt;/p&gt;
    &lt;p&gt;
      Post your photos:
      &lt;input type="file" multiple name="photos[]"&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input id="vehicle_bike" type="checkbox" name="vehicle[]" value="Bike" /&gt; &lt;label for="vehicle_bike"&gt;I have a bike&lt;/label&gt;&lt;br /&gt;
      &lt;input id="vehicle_car" type="checkbox" name="vehicle[]" value="Car" /&gt; &lt;label for="vehicle_car"&gt;I have a car&lt;/label&gt;
    &lt;/p&gt;
    &lt;p&gt;
      Describe yourself:&lt;br /&gt;
      &lt;textarea name="description" cols="50" rows="8"&gt;&lt;/textarea&gt;
    &lt;/p&gt;
    &lt;p&gt;
      &lt;input type="submit" value="Submit" /&gt;
    &lt;/p&gt;
  &lt;/fieldset&gt;
&lt;/form&gt;

&lt;/body&gt;
&lt;/html&gt;</pre>
</div>
<div class="note">
 <strong>Note:</strong> As we said,<strong> {{domxref("FormData")}} objects are not <a href="/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify" title="/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify">stringifiable</a> objects</strong>. If you want to stringify a submitted data, use <a href="#A_little_vanilla_framework" title="#A_little_vanilla_framework">the previous <em>pure</em>-AJAX example</a>. Note also that, although in this example there are some <code>file</code> {{ HTMLElement("input") }} fields, <strong>when you submit a form through the <code>FormData</code> API you do not need to use the <a href="/en-US/docs/DOM/FileReader" title="/en-US/docs/DOM/FileReader"><code>FileReader</code></a> API also</strong>: files are automatically loaded and uploaded.</div>
<h2 id="Get_last_modified_date">Get last modified date</h2>
<pre class="brush: js">function getHeaderTime () {
  alert(this.getResponseHeader("Last-Modified"));  /* A valid GMTString date or null */
}

var oReq = new XMLHttpRequest();
oReq.open("HEAD" /* use HEAD if you only need the headers! */, "yourpage.html", true);
oReq.onload = getHeaderTime;
oReq.send();</pre>
<h3 id="Do_something_when_last_modified_date_changes">Do something when last modified date changes</h3>
<p>Let's create these two functions:</p>
<pre class="brush: js">function getHeaderTime () {

  var
    nLastVisit = parseFloat(window.localStorage.getItem('lm_' + this.filepath)),
    nLastModif = Date.parse(this.getResponseHeader("Last-Modified"));

  if (isNaN(nLastVisit) || nLastModif &gt; nLastVisit) {
    window.localStorage.setItem('lm_' + this.filepath, Date.now());
    isFinite(nLastVisit) &amp;&amp; this.callback(nLastModif, nLastVisit);
  }

}

function ifHasChanged(sURL, fCallback) {
  var oReq = new XMLHttpRequest();
  oReq.open("HEAD" /* use HEAD - we only need the headers! */, sURL, true);
  oReq.callback = fCallback;
  oReq.filepath = sURL;
  oReq.onload = getHeaderTime;
  oReq.send();
}</pre>
<p>Test:</p>
<pre class="brush: js">/* Let's test the file "yourpage.html"... */

ifHasChanged("yourpage.html", function (nModif, nVisit) {
  alert("The page '" + this.filepath + "' has been changed on " + (new Date(nModif)).toLocaleString() + "!");
});</pre>
<p>If you want to know <strong>whether <em>the current page</em> has changed</strong>, please read the article about <a href="/en-US/docs/Web/API/document.lastModified" title="/en-US/docs/Web/API/document.lastModified"><code>document.lastModified</code></a>.</p>
<h2 id="Cross-site_XMLHttpRequest">Cross-site XMLHttpRequest</h2>
<p>Modern browsers support cross-site requests by implementing the web applications working group's <a href="/en-US/docs/HTTP_access_control" title="HTTP access control">Access Control for Cross-Site Requests</a> standard.  As long as the server is configured to allow requests from your web application's origin, <code>XMLHttpRequest</code> will work.  Otherwise, an <code>INVALID_ACCESS_ERR</code> exception is thrown.</p>
<h2 id="Bypassing_the_cache">Bypassing the cache</h2>
<p><span style="line-height: 1.572;">A, cross-browser compatible approach to bypassing the cache is to append a timestamp to the URL, being sure to include a "?" or "&amp;" as appropriate.  For example:</span></p>
<pre>http://foo.com/bar.html -&gt; http://foo.com/bar.html?12345
http://foo.com/bar.html?foobar=baz -&gt; http://foo.com/bar.html?foobar=baz&amp;12345
</pre>
<p>Since the local cache is indexed by URL, this causes every request to be unique, thereby bypassing the cache.</p>
<p>You can automatically adjust URLs using the following code:</p>
<pre class="brush:js">var oReq = new XMLHttpRequest();

oReq.open("GET", url + ((/\?/).test(url) ? "&amp;" : "?") + (new Date()).getTime(), true);
oReq.send(null);</pre>
<h2 id="Security">Security</h2>
<p>{{fx_minversion_note(3, "Versions of Firefox prior to Firefox 3 allowed you to set the preference <code>capability.policy.&lt;policyname&gt;.XMLHttpRequest.open&lt;/policyname&gt;</code> to <code>allAccess</code> to give specific sites cross-site access.  This is no longer supported.")}}</p>
<p>{{fx_minversion_note(5, "Versions of Firefox prior to Firefox 5 could use <code>netscape.security.PrivilegeManager.enablePrivilege(\"UniversalBrowserRead\");</code> to request cross-site access. This is no longer supported, even though it produces no warning and permission dialog is still presented.")}}</p>
<p>The recommended way to enable cross-site scripting is to use the <code>Access-Control-Allow-Origin </code> HTTP header in the response to the XMLHttpRequest.</p>
<h3 id="XMLHttpRequests_being_stopped">XMLHttpRequests being stopped</h3>
<p>If you end up with an XMLHttpRequest having <code>status=0</code> and <code>statusText=null</code>, it means that the request was not allowed to be performed. It was <code><a href="http://www.w3.org/TR/XMLHttpRequest/#dom-xmlhttprequest-unsent" title="http://www.w3.org/TR/XMLHttpRequest/#dom-xmlhttprequest-unsent">UNSENT</a></code>. A likely cause for this is when the <a href="http://www.w3.org/TR/XMLHttpRequest/#xmlhttprequest-origin" style="outline: 1px dotted; outline-offset: 0pt;"><code>XMLHttpRequest</code> origin</a> (at the creation of the XMLHttpRequest) has changed when the XMLHttpRequest is then <code>open()</code>. This case can happen for example when one has an XMLHttpRequest that gets fired on an onunload event for a window: the XMLHttpRequest gets in fact created when the window to be closed is still there, and then the request is sent (ie <code>open()</code>) when this window has lost its focus and potentially different window has gained focus. The way to avoid this problem is to set a listener on the new window "activate" event that gets set when the old window has its "unload" event fired.</p>
<h2 id="Using_XMLHttpRequest_from_JavaScript_modules_XPCOM_components">Using XMLHttpRequest from JavaScript modules / XPCOM components</h2>
<p>Instantiating <code>XMLHttpRequest</code> from a <a href="/en-US/docs/JavaScript_code_modules/Using" title="https://developer.mozilla.org/en/JavaScript_code_modules/Using_JavaScript_code_modules">JavaScript module</a> or an XPCOM component works a little differently; it can't be instantiated using the <code>XMLHttpRequest()</code> constructor. The constructor is not defined inside components and the code results in an error. The best way to work around this is to use the XPCOM component constructor.</p>
<pre class="brush: js">const XMLHttpRequest = Components.Constructor("@mozilla.org/xmlextras/xmlhttprequest;1", "nsIXMLHttpRequest");
</pre>
<p>Unfortunately in versions of Gecko prior to Gecko 16 there is a bug which can cause requests created this way to be cancelled for no reason.  If you need your code to work on Gecko 15 or earlier, you can get the XMLHttpRequest constructor from the hidden DOM window like so.</p>
<pre class="brush:js">const { XMLHttpRequest } = Components.classes["@mozilla.org/appshell/appShellService;1"]
                                     .getService(Components.interfaces.nsIAppShellService)
                                     .hiddenDOMWindow;
var oReq = new XMLHttpRequest();</pre>
<h2 id="See_also">See also</h2>
<ol>
 <li><a href="/en-US/docs/AJAX/Getting_Started" title="AJAX/Getting_Started">MDN AJAX introduction</a></li>
 <li><a href="/en-US/docs/HTTP_access_control" title="HTTP access control">HTTP access control</a></li>
 <li><a href="/en-US/docs/How_to_check_the_security_state_of_an_XMLHTTPRequest_over_SSL" title="How to check the security state of an XMLHTTPRequest over SSL">How to check the security state of an XMLHTTPRequest over SSL</a></li>
 <li><a href="http://www.peej.co.uk/articles/rich-user-experience.html">XMLHttpRequest - REST and the Rich User Experience</a></li>
 <li><a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/xmlsdk/html/xmobjxmlhttprequest.asp">Microsoft documentation</a></li>
 <li><a href="https://developer.apple.com/library/safari/documentation/AppleApplications/Conceptual/SafariJSProgTopics/Articles/XHR.html">Apple developers' reference</a></li>
 <li><a href="http://jibbering.com/2002/4/httprequest.html">"Using the XMLHttpRequest Object" (jibbering.com)</a></li>
 <li><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest Object: W3C Specification</a></li>
 <li><a href="http://dev.w3.org/2006/webapi/progress/Progress.html" title="http://dev.w3.org/2006/webapi/progress/Progress.html">Web Progress Events specification</a></li>
</ol>