错误提示

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

错误类型

警告。JavaScript 引擎不会停止运行。

哪里出错了？

非标准的泛型  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。

Firefox bug 1222552 对 String 泛型方法的移除进行了追踪。

示例

废弃的语法

var num = 15; 
String.replace(num, /5/, '2');

标准语法

var num = 15;
String(num).replace(/5/, '2');

垫片

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：

/*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]);
  }
}());

相关内容

• String
• Generics 同样存在于 Array 的方法中（也同样被废弃了）。