作用call和apply用来调用函数，并用指定对象（第一个参数）替换函数的 this 值，同时用指定数组替换函数的参数我自己不用声明一个构造函数，就借用现成的构造函数，从而精简代码代码<!DOCTYPE html><html lang=“en”><head> <meta charset=“UTF-8”> <meta name=“viewport” content=“width=device-width, initial-scale=1.0”> <meta http-equiv=“X-UA-Compatible” content=“ie=edge”> <title>Document</title></head><body> <script> var obj = { value: ‘1’ } function fn(name, age) { this.name = name; this.age = age; this.say = function() { alert(this.name + this.age) } } </script> <!– call –> <script> Function.prototype.call2 = function(context) { var context = context || window; context.fn = this; var args = []; for (var i = 1; i < arguments.length; i++) { args.push(‘arguments[’ + i + ‘]’); } var result = eval(‘context.fn(’ + args + ‘)’); delete context.fn return result; } fn.call(obj, ‘jie’, 10) obj.say() fn.call2(obj, ‘biao’, 20) obj.say() </script> <!– apply –> <script> Function.prototype.apply2 = function(context, arr) { var context = Object(context) || window; context.fn = this; var result; if (!arr) { result = context.fn(); } else { var args = []; for (var i = 0, len = arr.length; i < len; i++) { args.push(‘arr[’ + i + ‘]’); } result = eval(‘context.fn(’ + args + ‘)’) } delete context.fn return result; } fn.apply(obj, [‘jie’, 10]) obj.say() fn.apply2(obj, [‘biao’, 20]) obj.say() </script></body></html>效果