---
title: Function.arity
slug: Web/JavaScript/Reference/Global_Objects/Function/arity
translation_of: Archive/Web/JavaScript/Function.arity
---
<div>
<div>{{JSRef("Global_Objects", "Function")}} {{obsolete_header}}</div>
</div>

<h2 id="Summary" name="Summary">概述</h2>

<p>返回一个函数的形参数量.</p>

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

<p class="note"><code>arity</code>是一个古老的已经没有浏览器支持的属性,你应该使用<code><a href="/zh-CN/docs/JavaScript/Reference/Global_Objects/Function/length" title="JavaScript/Reference/Global_Objects/Function/length">Function.prototype.length</a></code>属性来代替.</p>