JavaScript 字典类

        function Dictionary(){
            var items = {};
            //验证一个key是否是items对象的一个属性
            this.has = function(key){
                return key in items;
            };
            //给字典添加一个新的值，或者用来更新一个已有的值
            this.set = function(key,value){
                items[key] = value;
            };
            this.remove = 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 = [];
                //遍历items对象的所有属性值
                for(var k in items){
                    //用has函数来验证key确实存在，然后将它的值加入values数组
                    if(this.has(k)){
                        values.push(items[k]);
                    }
                }
                //返回所有找到的值
                return values;
            };
            //返回items变量的方法
            this.getItems = function(){
                return items;
            };

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

            this.size = function(){
                return Object.keys(items).length;
            };


            this.keys = function(){
                return Object.keys(items);
            };


        }
        var dictionary = new Dictionary();
        dictionary.set('Gandalf','[email protected]');
        dictionary.set('John', '[email protected]');
        dictionary.set('Tyrion', '[email protected]');

        console.log(dictionary.has('Gandalf'));//返回true
        console.log(dictionary.size()); //3
        console.log(dictionary.keys());//["Gandalf", "John", "Tyrion"]
        console.log(dictionary.values()); //["[email protected]", "[email protected]", "[email protected]"]
        console.log(dictionary.get('Tyrion'));  //[email protected]
        dictionary.remove('John');
        console.log(dictionary.keys()); //["Gandalf", "Tyrion"]
        console.log(dictionary.values()); // ["[email protected]", "[email protected]"]
        console.log(dictionary.getItems()); //{Gandalf: "[email protected]", Tyrion: "[email protected]"}