1.首先，在新版本的浏览器中，已经实现了对Map的原生支持：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map

　查看一下，哪个浏览器的版本支持了Map，并且想想自己所需要的最低版本是否已被支持。

2.若没有，自己实现一个：

function Map() { // 定义Map对象    this.keys = new Array();    this.data = new Object();    this.put = function (key, value) {        if (this.data[key] == null) {            this.keys.push(key);        }        this.data[key] = value;    };    this.get = function (key) {        return this.data[key];    };    this.remove = function (key) {        this.keys.remove(key);        this.data[key] = null;    };    this.each = function (fn) {        if (typeof fn != 'function') {            return;        }        var len = this.keys.length;        for (var i = 0; i < len; i++) {            var k = this.keys[i];            fn(k, this.data[k], i);        }    };    this.entrys = function () {        var len = this.keys.length;        var entrys = new Array(len);        for (var i = 0; i < len; i++) {            entrys[i] = {                key: this.keys[i],                value: this.data[i]            };        }        return entrys;    };    this.isEmpty = function () {        return this.keys.length == 0;    };    this.size = function () {        return this.keys.length;    };} var map = new Map(); map.put("a","a"); map.put("b","b"); var data = ""; map.each(function(value, key){
    　　　　data += key; 　　} ); console.log(data);