算法学习--队列接口设计

let Queue = function(){
        this.items = [];

        /**
         * [add description]添加
         * @param {[type]} el [description]
         */
        Queue.prototype.add = function(el){
            return this.items.push(el);
        }
        /**
         * [element description]获取队列头元素
         * @return {[type]} [description]
         */
        Queue.prototype.element = function() {
            return this.items[0];
        } 
        /**
         * [poll description]移出并返回队列的头元素
         * @return {[type]} [description]
         */
        Queue.prototype.poll = function() {
            return this.items.shift();
        }
        /**
         * [isEmpty description]队列中是否有元素
         * @return {[type]} [description]
         */
        Queue.prototype.isEmpty = function() {
            let result = this.items.length > 0 ? false : true;
            return result;
        }
        /**
         * [size description]队列长度
         * @return {[type]} [description]
         */
        Queue.prototype.size = function() {
            return this.items.length;
        }
        /**
         * [clear description]清空队列
         * @return {[type]} [description]
         */
        Queue.prototype.clear = function(){
            return this.items = [];
        }
    }
    
    let queue = new Queue();
    console.log('isEmpty-- ',queue.isEmpty())
    queue.add('111');
    queue.add('222');
    queue.add('333');
    queue.add('444');

    console.log(queue)
    console.log('element-- ',queue.element())
    console.log('poll-- ',queue.poll())
    console.log('size-- ',queue.size())
    console.log('clear-- ',queue.clear())