算法学习--栈接口设计

function stack(){
        this.arr = [];

        /**
         * [size description]元素数量
         * @return {[type]} [description]
         */
        stack.prototype.size = function(){
            return this.arr.length
        }
        /**
         * [isEmpty description]是否为空
         * @return {Boolean} [description]
         */
        stack.prototype.isEmpty = function(){
            let result = this.arr.length > 0 ? false : true;
            return result;
        }
        /**
         * [push description]入栈
         * @param  {[type]} e [description]
         * @return {[type]}   [description]
         */
        stack.prototype.push = function(e){
            this.arr.push(e);
            return this.arr;
        }
        /**
         * [pop description]出栈
         * @return {[type]} [description]
         */
        stack.prototype.pop = function(){
            this.arr.splice(this.arr.length - 1,1);
            return this.arr;
        }
        /**
         * [top description]获取栈顶元素
         * @return {[type]} [description]
         */
        stack.prototype.top = function(){
            return this.arr[this.arr.length - 1];
        }
    }
    
    let stackTest = new stack();
    console.log('isEmpty-- ',stackTest.isEmpty());
    stackTest.push(11);
    stackTest.push(22);
    stackTest.push(33);
    stackTest.push(44);
    console.log('push-- ',stackTest);
    console.log('size-- ',stackTest.size());
    console.log('top-- ',stackTest.top());
    console.log('pop-- ',stackTest.pop());
    console.log('top-- ',stackTest.top());