用js来实现那些数据结构11（字典）

function Map () {    var items = {};    this.has = function (key) {        return key in items;    }    this.set = function (key,value) {        items[key] = value;    }    this.delete = function (key) {        if(this.has(key)) {            delete items[key];            return true;        }        return false;    }    this.get = function (key) {        return this.has(key) ? items[key] : undefined;    }    this.values = function () {        var values = [];        for(var k in items) {            if(this.has(k)) {                values.push(items[k])            }        }        return values;    }    this.keys = function () {        return  .keys(items);    }    this.getItems = function () {        return items;    }    this.clear = function() {        items = {};    }    this.size = function () {        return  .keys(items).length;    }}var map = new Map();map.set("zak","fat");map.set("lily","thin");map.set("david","big");map.set("jams","small");console.log(map.has("jams"));//trueconsole.log(map.has("zaking"));//falseconsole.log(map.size());//4console.log(map.keys());//["zak", "lily", "david", "jams"]console.log(map.values());//["fat", "thin", "big", "small"]console.log(map.get("zak"));//fatmap.delete("zak");console.log(map.has("zak"));//falseconsole.log(map.getItems());//{lily: "thin", david: "big", jams: "small"}