Revision 971623 of Performance

<div>{{APIRef("High Resolution Time")}}</div>

<p>The <strong><code>Performance</code></strong> interface represents timing-related performance information for the given page.</p>

<p>An object of this type can be obtained by calling the {{domxref("Window.performance")}} read-only attribute.</p>

<div class="note">
<p><strong><em>Note</em>: </strong>This interface and its members are available in <a href="/en-US/docs/Web/API/Web_Workers_API">Web Workers</a>, except where indicated below. Note that some available parts of the interface are not yet documented (see the <a href="https://www.w3.org/TR/performance-timeline/#sec-window.performance-attribute">Performance Timeline</a> and <a href="https://www.w3.org/TR/user-timing/#extensions-performance-interface">User Timing</a> specs for more details.) Also note that performance markers and measures are per context. If you create a mark on the main thread (or other worker), you cannot see it in a worker thread, and vice versa.</p>
</div>

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

<p><em>The <code>Performance</code> interface doesn't inherit any properties.</em></p>

<dl>
 <dt>{{domxref("Performance.timing")}} {{readonlyInline}} {{NotAvailableInWorkerInline}}</dt>
 <dd>Is a {{domxref("PerformanceTiming")}} object containing latency-related performance information.</dd>
 <dt>{{domxref("Performance.navigation")}} {{readonlyInline}} {{NotAvailableInWorkerInline}}</dt>
 <dd>Is a {{domxref("PerformanceNavigation")}} object representing the type of navigation that occurs in the given browsing context, like the amount of redirections needed to fetch the resource.</dd>
 <dt>{{domxref("Performance.onresourcetimingbufferfull")}}</dt>
 <dd>Is an {{domxref("EventTarget")}} which is a callback that will be called when the {{event("resourcetimingbufferfull")}} event is fired.</dd>
</dl>

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

<p><em><em>The <code>Performance</code> interface doesn't inherit any </em>method</em>.</p>

<dl>
 <dt>{{domxref("Performance.now()")}}</dt>
 <dd>Returns a {{domxref("DOMHighResTimeStamp")}} representing the amount of milliseconds elapsed since a reference instant.</dd>
 <dt>{{domxref("Performance.toJSON()")}} {{NotAvailableInWorkerInline}}</dt>
 <dd>Is a jsonizer returning a json object representing the <code>Performance</code> object.</dd>
 <dt>{{domxref("Performance.getEntries()")}}</dt>
 <dd>Returns a list of {{domxref("PerformanceEntry")}} objects based on the given <em>filter</em>.</dd>
 <dt>{{domxref("Performance.getEntriesByType()")}}</dt>
 <dd>Returns a list of {{domxref("PerformanceEntry")}} objects of the given <em>entry type</em>.</dd>
 <dt>{{domxref("Performance.getEntriesByName()")}}</dt>
 <dd>Returns a list of {{domxref("PerformanceEntry")}} objects based on the given <em>name</em> and <em>entry type</em>.</dd>
 <dt>{{domxref("Performance.clearResourceTimings()")}}</dt>
 <dd>Removes all {{domxref("PerformanceEntry","performance entries")}} with a {{domxref("PerformanceEntry.entryType","entryType")}} of "<code>resource</code>" from the browser's performance data buffer.</dd>
 <dt>{{domxref("Performance.setResourceTimingBufferSize()")}}</dt>
 <dd>Sets the browser's resource timing buffer size to the specified number of "<code>resource</code>" {{domxref("PerformanceEntry.entryType","type")}} {{domxref("PerformanceEntry","performance entry")}} objects.</dd>
</dl>

<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('Highres Time Level 2', '#the-performance-interface', 'toJSON()')}}</td>
   <td>{{Spec2('Highres Time Level 2')}}</td>
   <td>Defines <code>toJson()</code> method.</td>
  </tr>
  <tr>
   <td>{{SpecName('Highres Time', '#the-performance-interface', 'Performance')}}</td>
   <td>{{Spec2('Highres Time')}}</td>
   <td>Defines <code>now()</code> method.</td>
  </tr>
  <tr>
   <td>{{SpecName('Navigation Timing', '#sec-window.performance-attribute', 'Performance')}}</td>
   <td>{{Spec2('Navigation Timing')}}</td>
   <td>Defines <code>timing</code> and <code>navigation</code> properties.</td>
  </tr>
  <tr>
   <td>{{SpecName('Performance Timeline Level 2', '#extensions-to-the-performance-interface', 'Performance extensions')}}</td>
   <td>{{Spec2('Performance Timeline Level 2')}}</td>
   <td>Changes <code>getEntries()</code> interface.</td>
  </tr>
  <tr>
   <td>{{SpecName('Performance Timeline', '#sec-window.performance-attribute', 'Performance extensions')}}</td>
   <td>{{Spec2('Performance Timeline')}}</td>
   <td>Defines <code>getEntries()</code>, <code>getEntriesByType()</code> and <code>getEntriesByName()</code> methods.</td>
  </tr>
  <tr>
   <td>{{SpecName('Resource Timing', '#extensions-performance-interface', 'Performance extensions')}}</td>
   <td>{{Spec2('Resource Timing')}}</td>
   <td>Defines <code>clearResourceTimings()</code> and <code>setResourceTimingBufferSize()</code> methods and the <code>onresourcetimingbufferfull</code> property.</td>
  </tr>
  <tr>
   <td>{{SpecName('User Timing Level 2', '#extensions-performance-interface', 'Performance extensions')}}</td>
   <td>{{Spec2('User Timing Level 2')}}</td>
   <td>Clarifies <code>mark()</code>, <code>clearMark()</code>, <code>measure()</code> and <code>clearMeasure()</code> interfaces.</td>
  </tr>
  <tr>
   <td>{{SpecName('User Timing', '#extensions-performance-interface', 'Performance extensions')}}</td>
   <td>{{Spec2('User Timing')}}</td>
   <td>Defines <code>mark()</code>, <code>clearMark()</code>, <code>measure()</code> and <code>clearMeasure()</code> interfaces.</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 (<code>timing </code>attribute)</td>
   <td>6.0</td>
   <td>{{CompatGeckoDesktop("7.0")}}</td>
   <td>9.0</td>
   <td>15.0</td>
   <td>8</td>
  </tr>
  <tr>
   <td><code>navigation</code> attribute</td>
   <td>{{CompatChrome("9")}}</td>
   <td>{{CompatGeckoDesktop("7")}}</td>
   <td>9.0</td>
   <td>{{CompatOpera("15")}}</td>
   <td>8</td>
  </tr>
  <tr>
   <td><code>now()</code> on regular context</td>
   <td>{{ CompatChrome("20.0") }} {{ property_prefix("webkit") }}<br />
    {{ CompatChrome("24.0") }}</td>
   <td>{{ CompatGeckoDesktop("15.0") }}</td>
   <td>10.0</td>
   <td>{{CompatVersionUnknown()}}</td>
   <td>8</td>
  </tr>
  <tr>
   <td><code>now()</code> in Web workers.</td>
   <td>{{ CompatChrome("33.0") }}</td>
   <td>{{ CompatGeckoDesktop("34.0") }}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
  <tr>
   <td><code>toJSON()</code></td>
   <td>{{CompatNo}}</td>
   <td>{{CompatGeckoDesktop("25.0")}}</td>
   <td>9.0</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>getEntries()</code>, <code>getEntriesByType()</code>, <code>getEntriesByName()</code></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>clearResourceTimings()</code>, <code>setResourceTimingBufferSize()</code></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>onresourcetimingbufferfull</code></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>mark()</code>, <code>clearMark()</code>, <code>measure()</code>, <code>clearMeasure()</code></td>
   <td>43</td>
   <td>41</td>
   <td>10</td>
   <td>33</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><strong>Firefox OS</strong></th>
   <th>IE Phone</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatGeckoMobile("7.0")}}</td>
   <td>{{CompatGeckoFxOS("7.0")}}</td>
   <td>9.0</td>
   <td>15.0</td>
   <td>9</td>
  </tr>
  <tr>
   <td><code>navigation</code> attribute</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>9.0</td>
   <td>{{CompatNo}}</td>
   <td>9</td>
  </tr>
  <tr>
   <td><code>now()</code> on regular context</td>
   <td>{{ CompatChrome("20.0") }} {{ property_prefix("webkit") }}<br />
    {{ CompatChrome("24.0") }}</td>
   <td>{{ CompatGeckoMobile("15.0") }}</td>
   <td>{{ CompatGeckoFxOS("15.0") }}</td>
   <td>10.0</td>
   <td>{{CompatNo}}</td>
   <td>9</td>
  </tr>
  <tr>
   <td><code>now()</code> in Web workers.</td>
   <td>{{CompatUnknown}}</td>
   <td>{{ CompatGeckoMobile("34.0") }}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
  <tr>
   <td><code>toJSON()</code></td>
   <td>{{CompatNo}}</td>
   <td>{{CompatGeckoMobile("25.0")}}</td>
   <td>{{CompatGeckoFxOS("25.0")}}</td>
   <td>10.0</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatUnknown}}</td>
  </tr>
  <tr>
   <td><code>getEntries()</code>, <code>getEntriesByType()</code>, <code>getEntriesByName()</code></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatGeckoMobile("25.0")}}</td>
   <td>{{CompatGeckoFxOS("25.0")}}</td>
   <td>10.0</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>clearResourceTimings()</code>, <code>setResourceTimingBufferSize()</code></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>onresourcetimingbufferfull</code></td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatNo}}</td>
  </tr>
  <tr>
   <td><code>mark()</code>, <code>clearMark()</code>, <code>measure()</code>, <code>clearMeasure()</code></td>
   <td>46</td>
   <td>42</td>
   <td>42</td>
   <td>10</td>
   <td>33</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>