2.参考课本代码，完成队列的链式存储结构的定义、构造、销毁、出队、

   
//在javascript中，可以使用数组来实现一个队列
function stack(){
this.datastore = new Array();    //初始化
this.isEmpty = isEmpty; //判断队空
this.isFull = isFull;   //判断队满
this.add = add;         //入队
this.remove = remove;   //出队
this.count = 0;

function isEmpty(){
if(this.count == 0) return true;
return false;
}

function isFull(){
if(!isEmpty()) return true;
return false;
}

function add(value){
alert(this.count);
this.datastore[this.count ++] = value;
}

function remove(){
if(this.count <= 0) {
this.count = 0;
alert('当前队列为空，无法删除！');
return;
}
delete this.datastore[-- this.count ];
}

}