---
title: 'SyntaxError: "0"-prefixed octal literals and octal escape seq. are deprecated'
slug: Web/JavaScript/Reference/Errors/Deprecated_octal
tags:
  - JavaScript
  - 严格模式
  - 语法错误
  - 错误提示
translation_of: Web/JavaScript/Reference/Errors/Deprecated_octal
---
<div>{{jsSidebar("Errors")}}</div>

<h2 id="错误提示">错误提示</h2>

<pre class="syntaxbox">SyntaxError:
"0"-prefixed octal literals and octal escape sequences are deprecated;
for octal literals use the \"0o\" prefix instead
</pre>

<h2 id="错误类型">错误类型</h2>

<p>语法错误（{{jsxref("SyntaxError")}} ），只出现于<a href="/en-US/docs/Web/JavaScript/Reference/Strict_mode">严格模式</a>下。</p>

<h2 id="哪里出错了？">哪里出错了？</h2>

<p>八进制字面量与八进制转义序列语法已经被废弃，在严格模式下会报语法错误（{{jsxref("SyntaxError")}}）。在 ECMAScript 2015 及以后的规范中，标准语法是前导 0 后面跟一个大写或小写的拉丁文字母 "O" (<code>0o</code> 或 <code>0O)。</code></p>

<h2 id="示例">示例</h2>

<h3 id="前导0形式的八进制字面量">前导"0"形式的八进制字面量</h3>

<pre class="brush: js example-bad">"use strict";

03;

// SyntaxError: "0"-prefixed octal literals and octal escape sequences
// are deprecated</pre>

<h3 id="八进制转义序列">八进制转义序列</h3>

<pre class="brush: js example-bad">"use strict";

"\251";

// SyntaxError: "0"-prefixed octal literals and octal escape sequences
// are deprecated
</pre>

<h3 id="合法的八进制数字">合法的八进制数字</h3>

<p>使用前导 0 后面跟字母 "o" 或 "O" 的形式：</p>

<pre class="brush: js example-good">0o3;
</pre>

<p>至于八进制转义序列，你可以使用十六进制转义序列来代替：</p>

<pre class="brush: js example-good">'\xA9';</pre>

<h2 id="相关内容">相关内容</h2>

<ul>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#Octal">Lexical grammar</a></li>
 <li>
  <p><a href="/en-US/docs/Web/JavaScript/Reference/Errors/Bad_octal">警告： 08/09 不是符合 ECMA-262 规范的八进制常量</a></p>
 </li>
</ul>