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---
title: 'Warning: String.x is deprecated; use String.prototype.x instead'
slug: Web/JavaScript/Reference/Errors/Deprecated_String_generics
tags:
- JavaScript
- 警告
translation_of: Web/JavaScript/Reference/Errors/Deprecated_String_generics
---
<div>{{jsSidebar("Errors")}}</div>
<h2 id="错误提示">错误提示</h2>
<pre class="syntaxbox">Warning: String.charAt is deprecated; use String.prototype.charAt instead
Warning: String.charCodeAt is deprecated; use String.prototype.charCodeAt instead
Warning: String.concat is deprecated; use String.prototype.concat instead
Warning: String.contains is deprecated; use String.prototype.contains instead
Warning: String.endsWith is deprecated; use String.prototype.endsWith instead
Warning: String.includes is deprecated; use String.prototype.includes instead
Warning: String.indexOf is deprecated; use String.prototype.indexOf instead
Warning: String.lastIndexOf is deprecated; use String.prototype.lastIndexOf instead
Warning: String.localeCompare is deprecated; use String.prototype.localeCompare instead
Warning: String.match is deprecated; use String.prototype.match instead
Warning: String.normalize is deprecated; use String.prototype.normalize instead
Warning: String.replace is deprecated; use String.prototype.replace instead
Warning: String.search is deprecated; use String.prototype.search instead
Warning: String.slice is deprecated; use String.prototype.slice instead
Warning: String.split is deprecated; use String.prototype.split instead
Warning: String.startsWith is deprecated; use String.prototype.startsWith instead
Warning: String.substr is deprecated; use String.prototype.substr instead
Warning: String.substring is deprecated; use String.prototype.substring instead
Warning: String.toLocaleLowerCase is deprecated; use String.prototype.toLocaleLowerCase instead
Warning: String.toLocaleUpperCase is deprecated; use String.prototype.toLocaleUpperCase instead
Warning: String.toLowerCase is deprecated; use String.prototype.toLowerCase instead
Warning: String.toUpperCase is deprecated; use String.prototype.toUpperCase instead
Warning: String.trim is deprecated; use String.prototype.trim instead
Warning: String.trimLeft is deprecated; use String.prototype.trimLeft instead
Warning: String.trimRight is deprecated; use String.prototype.trimRight instead
</pre>
<h2 id="错误类型">错误类型</h2>
<p>警告。JavaScript 引擎不会停止运行。</p>
<h2 id="哪里出错了？">哪里出错了？</h2>
<p>非标准的泛型 {{jsxref("String")}} 方法已经被废弃，将来会被移除（这些方法仅在 Firefox 浏览器中得到实现）。String 泛型在 String 对象上提供了一系列的 String 实例方法，使得这些 String 方法可以应用于任何类型的对象。</p>
<p>Firefox {{bug(1222552)}} 对 String 泛型方法的移除进行了追踪。</p>
<h2 id="示例">示例</h2>
<h3 id="废弃的语法">废弃的语法</h3>
<pre class="brush: js example-bad">var num = 15;
String.replace(num, /5/, '2');</pre>
<h3 id="标准语法">标准语法</h3>
<pre class="brush: js example-good">var num = 15;
String(num).replace(/5/, '2');
</pre>
<h2 id="垫片">垫片</h2>
<p>以下是一个垫片脚本来为不支持 String 泛型方法浏览器提供支持：</p>
<pre class="brush: js">/*globals define*/
// Assumes all supplied String instance methods already present
// (one may use shims for these if not available)
(function() {
'use strict';
var i,
// We could also build the array of methods with the following, but the
// getOwnPropertyNames() method is non-shimable:
// Object.getOwnPropertyNames(String).filter(function(methodName) {
// return typeof String[methodName] === 'function';
// });
methods = [
'contains', 'substring', 'toLowerCase', 'toUpperCase', 'charAt',
'charCodeAt', 'indexOf', 'lastIndexOf', 'startsWith', 'endsWith',
'trim', 'trimLeft', 'trimRight', 'toLocaleLowerCase', 'normalize',
'toLocaleUpperCase', 'localeCompare', 'match', 'search', 'slice',
'replace', 'split', 'substr', 'concat', 'localeCompare'
],
methodCount = methods.length,
assignStringGeneric = function(methodName) {
var method = String.prototype[methodName];
String[methodName] = function(arg1) {
return method.apply(arg1, Array.prototype.slice.call(arguments, 1));
};
};
for (i = 0; i < methodCount; i++) {
assignStringGeneric(methods[i]);
}
}());</pre>
<h2 id="相关内容">相关内容</h2>
<ul>
<li>{{jsxref("String")}}</li>
<li>{{jsxref("Global_Objects/Array", "Generics", "#Array_generic_methods", 1)}} 同样存在于 {{jsxref("Array")}} 的方法中（也同样被废弃了）。</li>
</ul>
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