字典 Dictionary类

/*字典 Dictionary类*/function Dictionary() {    this.add = add;    this.datastore = new Array();    this.find = find;    this.remove = remove;    this.showAll = showAll;    this.count = count;    this.clear = clear;}function add(key, value) {    this.datastore[key] = value;}function find(key) {    return this.datastore[key];}function remove(key) {    delete this.datastore[key];}function showAll() {    var str = "";    for(var key in this.datastore) {        str += key + " -> " + this.datastore[key] + ";  "    }    console.log(str);}function count() {    /*var ss = Object.keys(this.datastore).length;    console.log("ssss   "+ss);    return Object.keys(this.datastore).length;*/    /**/    var n = 0;    for(var key in Object.keys(this.datastore)) {        ++n;    }    console.log(n);    return n;}function clear() {    for(var key in this.datastore) {        delete this.datastore[key];    }}var pbook = new Dictionary();pbook.add("Mike", "723");pbook.add("Jennifer", "987");pbook.add("Jonathan", "666");pbook.showAll();//Mike -> 723;  Jennifer -> 987;  Jonathan -> 666;pbook.count();//3pbook.remove("Jennifer");//pbook.clear();pbook.showAll();//Mike -> 723;  Jonathan -> 666;pbook.count();//2