Revision 974265 of PerformanceResourceTiming

<div>{{APIRef("Resource Timing API")}}</div>

<p>The <strong><code>PerformanceResourceTiming</code></strong> interface enables retrieving and analyzing detailed network timing data regarding the loading of an application's <em>resources</em>. An application can use the timing metrics to determine, for example, the length of time it takes to fetch a specific resource such as an {{domxref("XMLHttpRequest")}}, {{SVGElement("SVG","SVG element")}}, image, script, etc.).</p>

<p>The {{domxref("PerformanceEntry","performance entry")}} properties extended by this interface create a <em>resource loading timeline</em> with {{domxref("DOMHighResTimeStamp","high resolution timestamps")}} for network events such as redirect start and end times, fetch start, DNS lookup start and end times, response start and end times, etc. Additionally, the interface extends {{domxref("PerformanceEntry","performance entries")}} with other properties which provide data about the size of the fetched resource as well as the <em>type</em> of resource that initiated the fetch.</p>

<p class="note">The <code>PerformanceResourceTiming</code> interface has no properties, no methods nor any constructors. However, it extends the {{domxref("PerformanceEntry")}} interface with several properties (listed in the {{domxref("PerformanceEntry")}} reference).<br />
 <code>PerformanceResourceTiming</code> also extends the following {{domxref("PerformanceEntry","PerformanceEntry")}} properties: {{domxref("PerformanceEntry.name","name")}}, {{domxref("PerformanceEntry.entryType","entryType")}}, {{domxref("PerformanceEntry.startTime","startTime")}} and {{domxref("PerformanceEntry.duration","duration")}} with additional constraints/qualifications for "<code>resource</code>" {{domxref("PerformanceEntry.entryType","performance entry types")}}.</p>

<h2 id="Properties">Properties</h2>

<p>This interface has no properties but it extends the following {{domxref("PerformanceEntry")}} properties by qualifying/constrainting the properties as follows:</p>

<dl>
 <dt>{{domxref("PerformanceEntry.entryType","entryType")}}</dt>
 <dd>Set to "<code>resource</code>".</dd>
 <dt>{{domxref("PerformanceEntry.name","name")}}</dt>
 <dd>Set to the resource's URL.</dd>
 <dt>{{domxref("PerformanceEntry.startTime","startTime")}}</dt>
 <dd>Set to the {{domxref("DOMHighResTimeStamp","timestamp")}} immediately before the browser to {{domxref("PerformanceEntry.fetchStart","fetch the resource")}}.</dd>
 <dt>{{domxref("PerformanceEntry.duration","duration")}}</dt
 <dd>Set to the difference between the resource's {{domxref("PerformanceEntry.responseEnd","responseEnd")}} {{domxref("DOMHighResTimeStamp","timestamp")}} and its {{domxref("PerformanceEntry.startTime","startTime")}} {{domxref("DOMHighResTimeStamp","timestamp")}}.</dd>
</dl>

<h2 id="Methods">Methods</h2>

<p>This interface has no methods. It extends the {{domxref("PerformanceEntry.toJson","PerformanceEntry.toJSON()")}} method with additional constraints/qualifications for "<code>resource</code>" {{domxref("PerformanceEntry.entryType","performance entry types")}}.</p>

<h2 id="Example">Example</h2>

<p>See the example in <a href="/Web/API/Resource_Timing_API/Using_the_Resource_Timing_API">Using the Resource Timing API</a>.</p>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('Resource Timing', '#performanceresourcetiming', 'PerformanceResourceTiming')}}</td>
   <td>{{Spec2('Resource Timing')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support.</td>
   <td>43</td>
   <td>40</td>
   <td>10</td>
   <td>32</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS</th>
   <th>IE Phone</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support.</td>
   <td>4.4</td>
   <td>42</td>
   <td>{{CompatUnknown}}</td>
   <td>10.0</td>
   <td>32</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{domxref("PerformanceEntry")}}</li>
 <li><a href="/Web/API/Resource_Timing">Resource Timing (Overview)</a></li>
 <li><a href="/Web/API/Resource_Timing_API/Using_the_Resource_Timing_API">Using the Resource Timing API</a></li>
</ul>