---
title: 'RangeError: argument is not a valid code point'
slug: Web/JavaScript/Reference/Errors/Not_a_codepoint
translation_of: Web/JavaScript/Reference/Errors/Not_a_codepoint
---
<div>{{jsSidebar("Errors")}}</div>

<h2 id="错误信息">错误信息</h2>

<pre class="syntaxbox">RangeError: {0} is not a valid code point (Firefox)
RangeError: Invalid code point {0} (Chrome)
</pre>

<h2 id="错误类型">错误类型</h2>

<p>{{jsxref("RangeError")}}</p>

<h2 id="什么地方出错了？">什么地方出错了？</h2>

<p> {{jsxref("String.fromCodePoint()")}} 这个方法只能接受有效的码位（code point） 。</p>

<p>码位（ <a href="https://en.wikipedia.org/wiki/Code_point">code point</a>）是组成码空间（或代码页）的数值，范围是 0 到 0x10FFFF。</p>

<p> {{jsxref("NaN")}}，负整数（-1），非整数（3.14），或编号大于0x10FFFF (1114111) 的字符，无法使用该方法。</p>

<h2 id="范例">范例</h2>

<h3 id="无效的例子">无效的例子</h3>

<pre class="brush: js example-bad">String.fromCodePoint('_');      // RangeError
String.fromCodePoint(Infinity); // RangeError
String.fromCodePoint(-1);       // RangeError
String.fromCodePoint(3.14);     // RangeError
String.fromCodePoint(3e-2);     // RangeError
String.fromCodePoint(NaN);      // RangeError</pre>

<h3 id="有效的例子">有效的例子</h3>

<pre class="brush: js example-good">String.fromCodePoint(42);       // "*"
String.fromCodePoint(65, 90);   // "AZ"
String.fromCodePoint(0x404);    // "\u0404"
String.fromCodePoint(0x2F804);  // "\uD87E\uDC04"
String.fromCodePoint(194564);   // "\uD87E\uDC04"
String.fromCodePoint(0x1D306, 0x61, 0x1D307) // "\uD834\uDF06a\uD834\uDF07"
</pre>

<h2 id="相关链接">相关链接</h2>

<ul>
 <li>{{jsxref("String.fromCodePoint()")}}</li>
</ul>