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 Object.keys(items);
    }

    this.getItems = function () {
        return items;
    }

    this.clear = function() {
        items = {};
    }

    this.size = function () {
        return Object.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"));//true
console.log(map.has("zaking"));//false

console.log(map.size());//4
console.log(map.keys());//["zak", "lily", "david", "jams"]
console.log(map.values());//["fat", "thin", "big", "small"]
console.log(map.get("zak"));//fat

map.delete("zak");
console.log(map.has("zak"));//false
console.log(map.getItems());//{lily: "thin", david: "big", jams: "small"}