---
title: String.fromCodePoint()
slug: Web/JavaScript/Reference/Global_Objects/String/fromCodePoint
translation_of: Web/JavaScript/Reference/Global_Objects/String/fromCodePoint
---
<div>{{JSRef}}</div>

<p><strong><code>String.fromCodePoint()</code> 静态方法返回使用指定的代码点序列创建的字符串。</strong></p>

<div>{{EmbedInteractiveExample("pages/js/string-fromcodepoint.html")}}</div>



<h2 id="语法">语法</h2>

<pre class="syntaxbox"><code>String.fromCodePoint(<var>num1</var>[, ...[, <var>numN</var>]])</code></pre>

<h3 id="参数">参数</h3>

<dl>
 <dt><code>num1, ..., num<em>N</em></code></dt>
 <dd>一串 Unicode 编码位置，即“代码点”。</dd>
 <dt>
 <h3 id="返回值">返回值</h3>

 <p>使用指定的 Unicode 编码位置创建的字符串。</p>
 </dt>
</dl>

<h3 id="异常">异常</h3>

<dl>
 <dt>{{jsxref("RangeError")}}</dt>
 <dd>如果传入无效的 Unicode 编码，将会抛出一个{{jsxref("RangeError")}} (例如： "RangeError: NaN is not a valid code point")。</dd>
</dl>

<h2 id="说明">说明</h2>

<p>该方法返回一个字符串，而不是一个 {{jsxref("String")}} 对象。</p>

<p>因为 <code>fromCodePoint()</code> 是 {{jsxref("String")}} 的一个静态方法，所以只能通过 <code>String.fromCodePoint()</code> 这样的方式来使用，不能在你创建的 {{jsxref("String")}} 对象实例上直接调用。</p>

<h2 id="例子">例子</h2>

<h3 id="使用_fromCodePoint()">使用 <code>fromCodePoint()</code></h3>

<pre class="brush: js">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"

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>

<pre class="brush: js">// String.fromCharCode() 方法不能单独获取在高代码点位上的字符
// 另一方面，下列的示例中，可以返回 4 字节，也可以返回 2 字节的字符
// (也就是说，它可以返回单独的字符，使用长度 2 代替 1!）
console.log(String.fromCodePoint(0x2F804)); // or 194564 in decimal
</pre>

<h2 id="Polyfill">Polyfill</h2>

<p><code>String.fromCodePoint</code> 方法是 ECMAScript2015（ES6）新增加的特性，所以一些老的浏览器可能还不支持。可以通过使用下面的 polyfill 代码来保证浏览器的支持：</p>

<pre class="brush: js">if (!String.fromCodePoint) (function(stringFromCharCode) {
    var fromCodePoint = function(_) {
      var codeUnits = [], codeLen = 0, result = "";
      for (var index=0, len = arguments.length; index !== len; ++index) {
        var codePoint = +arguments[index];
        // correctly handles all cases including `NaN`, `-Infinity`, `+Infinity`
        // The surrounding `!(...)` is required to correctly handle `NaN` cases
        // The (codePoint&gt;&gt;&gt;0) === codePoint clause handles decimals and negatives
        if (!(codePoint &lt; 0x10FFFF &amp;&amp; (codePoint&gt;&gt;&gt;0) === codePoint))
          throw RangeError("Invalid code point: " + codePoint);
        if (codePoint &lt;= 0xFFFF) { // BMP code point
          codeLen = codeUnits.push(codePoint);
        } else { // Astral code point; split in surrogate halves
          // https://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
          codePoint -= 0x10000;
          codeLen = codeUnits.push(
            (codePoint &gt;&gt; 10) + 0xD800,  // highSurrogate
            (codePoint % 0x400) + 0xDC00 // lowSurrogate
          );
        }
        if (codeLen &gt;= 0x3fff) {
          result += stringFromCharCode.apply(null, codeUnits);
          codeUnits.length = 0;
        }
      }
      return result + stringFromCharCode.apply(null, codeUnits);
    };
    try { // IE 8 only supports `Object.defineProperty` on DOM elements
      Object.defineProperty(String, "fromCodePoint", {
        "value": fromCodePoint, "configurable": true, "writable": true
      });
    } catch(e) {
      String.fromCodePoint = fromCodePoint;
    }
}(String.fromCharCode));
</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">规范</th>
   <th scope="col">状态</th>
   <th scope="col">备注</th>
  </tr>
  <tr>
   <td>{{SpecName('ES2015', '#sec-string.fromcodepoint', 'String.fromCodePoint')}}</td>
   <td>{{Spec2('ES2015')}}</td>
   <td>Initial definition.</td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-string.fromcodepoint', 'String.fromCodePoint')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>{{Compat("javascript.builtins.String.fromCodePoint")}}</p>

<h2 id="参见">参见</h2>

<ul>
 <li>{{jsxref("String.fromCharCode()")}}</li>
 <li>{{jsxref("String.prototype.charAt()")}}</li>
 <li>{{jsxref("String.prototype.codePointAt()")}}</li>
 <li>{{jsxref("String.prototype.charCodeAt()")}}</li>
</ul>