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---
title: PerformanceEntry.duration
slug: Web/API/PerformanceEntry/duration
translation_of: Web/API/PerformanceEntry/duration
---
<div>{{APIRef("Performance Timeline API")}}</div>
<p>The <strong><code>duration</code></strong> property returns a {{domxref("DOMHighResTimeStamp","timestamp")}} that is the duration of the {{domxref("PerformanceEntry","performance entry")}}.</p>
<p>The value returned by this property depends on the performance entry's {{domxref("PerformanceEntry.entryType","type")}}:</p>
<ul>
<li>"<code>frame</code>" - returns a {{domxref("DOMHighResTimeStamp","timestamp")}} indicating the difference between the <code>startTime</code>s of two successive frames.</li>
<li>"<code>mark</code>" - returns "<code>0</code>" (a mark has no duration).</li>
<li>"<code>measure</code>" - returns the {{domxref("DOMHighResTimeStamp","timestamp")}} that is the duration of the measure.</li>
<li>"<code>navigation</code>" - returns the {{domxref("DOMHighResTimeStamp","timestamp")}} that is the difference between the {{domxref("PerformanceEntry.loadEventEnd")}} and {{domxref("PerformanceEntry.startTime")}} properties, respectively.例如： entry.entryType "navigation"，entry.duration 3611.26, entry.loadEventEnd 3611.2672285754975, entry.startTime 0；</li>
<li>"<code>resource</code>" - 返回 resource 的{{domxref("PerformanceEntry.responseEnd","responseEnd")}} {{domxref("DOMHighResTimeStamp","timestamp")}} 和 {{domxref("PerformanceEntry.startTime","startTime")}} {{domxref("DOMHighResTimeStamp","timestamp")}}的时间差. 例如： entry.entryType "resource"，entry.duration 901.1400000000001, entry.responseEnd 2527.82, entry.startTime 1626.68， 2527.82 - 1626.68 == 901.1400000000001；</li>
</ul>
<p>This property is {{readonlyInline}}.</p>
<h2 id="Syntax" name="Syntax">Syntax</h2>
<pre class="syntaxbox"><em>entry</em>.duration;</pre>
<h3 id="Return_Value" name="Return_Value">Return value</h3>
<p>A {{domxref("DOMHighResTimeStamp")}} representing the duration of the {{domxref("PerformanceEntry","performance entry")}}. If the duration concept doesn't apply for a particular performance metric, the browser may choose to return a duration of 0.</p>
<p class="note">Note: if the performance entry has an {{domxref("PerformanceEntry.entryType","entryType")}} of "<code>resource</code>" (i.e. the entry is a {{domxref("PerformanceResourceTiming")}} object), this property returns the difference between the {{domxref("PerformanceEntry.responseEnd")}} and {{domxref("PerformanceEntry.startTime")}} {{domxref("DOMHighResTimeStamp","timestamps")}}.</p>
<h2 id="Example">Example</h2>
<p>The following example shows the use of the <code>duration</code> property.</p>
<pre class="brush: js">function run_PerformanceEntry() {
log("PerformanceEntry support ...");
if (performance.mark === undefined) {
log("... performance.mark Not supported");
return;
}
// Create some performance entries via the mark() method
performance.mark("Begin");
do_work(50000);
performance.mark("End");
// Use getEntries() to iterate through the each entry
var p = performance.getEntries();
for (var i=0; i < p.length; i++) {
log("Entry[" + i + "]");
check_PerformanceEntry(p[i]);
}
}
function check_PerformanceEntry(obj) {
var properties = ["name", "entryType", "startTime", "duration"];
var methods = ["toJSON"];
for (var i=0; i < properties.length; i++) {
// check each property
var supported = properties[i] in obj;
if (supported)
log("..." + properties[i] + " = " + obj[properties[i]]);
else
log("..." + properties[i] + " = Not supported");
}
for (var i=0; i < methods.length; i++) {
// check each method
var supported = typeof obj[methods[i]] == "function";
if (supported) {
var js = obj[methods[i]]();
log("..." + methods[i] + "() = " + JSON.stringify(js));
} else {
log("..." + methods[i] + " = Not supported");
}
}
}
</pre>
<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('Performance Timeline Level 2', '#dom-performanceentry-duration', 'duration')}}</td>
<td>{{Spec2('Performance Timeline Level 2')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('Performance Timeline', '#dom-performanceentry-duration', 'duration')}}</td>
<td>{{Spec2('Performance Timeline')}}</td>
<td>Initial definition.</td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility">Browser compatibility</h2>
<div>
<div>
<p>{{Compat("api.PerformanceEntry.duration")}}</p>
</div>
</div>
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