---
title: Math.cos()
slug: Web/JavaScript/Reference/Global_Objects/Math/cos
translation_of: Web/JavaScript/Reference/Global_Objects/Math/cos
---
<div>
 {{JSRef("Global_Objects", "Math")}}</div>
<h2 id="Summary" name="Summary">概述</h2>
<p><code><strong>Math.cos()</strong></code> 函数返回一个数值的余弦值。</p>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox">Math.cos(<em>x</em>)</pre>
<h3 id="Parameters" name="Parameters">参数</h3>
<dl>
 <dt>
  <code>x</code></dt>
 <dd>
  一个以弧度为单位的数值。</dd>
</dl>
<h2 id="Description" name="Description">描述</h2>
<p><code>cos</code> 方法返回一个 -1 到 1 之间的数值，表示角度（单位：弧度）的余弦值。</p>
<p>由于 <code>cos</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.cos()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p>
<h2 id="Examples" name="Examples">示例</h2>
<h3 id="Example:_Using_Math.cos" name="Example:_Using_Math.cos">例子：使用 <code>Math.cos</code></h3>
<pre class="brush:js">Math.cos(0);           // 1
Math.cos(1);           // 0.5403023058681398

Math.cos(Math.PI);     // -1
Math.cos(2 * Math.PI); // 1
</pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">规范版本</th>
   <th scope="col">规范状态</th>
   <th scope="col">注解</th>
  </tr>
  <tr>
   <td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td>
   <td>Standard</td>
   <td>Initial definition.</td>
  </tr>
  <tr>
   <td>{{SpecName('ES5.1', '#sec-15.8.2.7', 'Math.cos')}}</td>
   <td>{{Spec2('ES5.1')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-math.cos', 'Math.cos')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
<p>{{ CompatibilityTable() }}</p>
<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</th>
   </tr>
   <tr>
    <td>Basic support</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
   </tr>
  </tbody>
 </table>
</div>
<div id="compat-mobile">
 <table class="compat-table">
  <tbody>
   <tr>
    <th>Feature</th>
    <th>Android</th>
    <th>Chrome for Android</th>
    <th>Firefox Mobile (Gecko)</th>
    <th>IE Mobile</th>
    <th>Opera Mobile</th>
    <th>Safari Mobile</th>
   </tr>
   <tr>
    <td>Basic support</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
    <td>{{ CompatVersionUnknown() }}</td>
   </tr>
  </tbody>
 </table>
</div>
<h2 id="See_also" name="See_also">相关链接</h2>
<ul>
 <li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li>
</ul>