---
title: arguments.length
slug: Web/JavaScript/Reference/Functions/arguments/length
translation_of: Web/JavaScript/Reference/Functions/arguments/length
---
<div>{{jsSidebar("Functions")}}</div>

<p>本次函数调用时传入函数的实参数量.</p>

<h2 id="Syntax">Syntax</h2>

<pre class="syntaxbox">arguments.length</pre>

<h2 id="Description" name="Description">描述</h2>

<p>arguments.length表示的是实际上向函数传入了多少个参数,这个数字可以比形参数量大,也可以比形参数量小(形参数量的值可以通过<a href="/zh-CN/docs/JavaScript/Reference/Global_Objects/Function/length" title="JavaScript/Reference/Global Objects/Function/length">Function.length</a>获取到).</p>

<h2 id="Examples" name="Examples">例子</h2>

<h3 id="Example:_Using_arguments.length" name="Example:_Using_arguments.length">例子: 使用<code>arguments.length</code></h3>

<p>这个例中,我们定义了一个可以相加任意个数字的函数.</p>

<pre class="brush: js">function adder(base, /*, n2, ... */) {
  base = Number(base);
  for (var i = 0; i &lt; arguments.length; i++) {
    base += Number(arguments[i]);
  }
  return base;
}
</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('ES1')}}</td>
   <td>{{Spec2('ES1')}}</td>
   <td>Initial definition. Implemented in JavaScript 1.1</td>
  </tr>
  <tr>
   <td>{{SpecName('ES5.1', '#sec-10.6', 'Arguments Object')}}</td>
   <td>{{Spec2('ES5.1')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-arguments-exotic-objects', 'Arguments Exotic Objects')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-arguments-exotic-objects', 'Arguments Exotic Objects')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器支持">浏览器支持</h2>



<p>{{Compat("javascript.functions.arguments.length")}}</p>

<h2 id="See_also" name="See_also">相关链接</h2>

<ul>
 <li><a href="/zh-CN/docs/JavaScript/Reference/Global_Objects/Function/length" title="JavaScript/Reference/Global_Objects/Function/length">Function.length</a></li>
</ul>