队列的实现

    function Queue() {
        this.dataStore = [];
        this.enqueue = enqueue;
        this.dequeue = dequeue;
        this.front = front;
        this.back = back;
        this.toString = toString;
        this.empty = empty;
    }
    function enqueue(element) {//向队尾添加一个元素
        this.dataStore.push(element);
    }
    function dequeue() {//删除队首的元素
        return this.dataStore.shift();
    }
    function front() {//读取队首元素
        return this.dataStore[0];
    }
    function back() {//读取队尾元素
        return this.dataStore[this.dataStore.length - 1];
    }
    function toString() {
        var retStr = "";
        for ( var i = 0; i < this.dataStore.length; ++i) {
            retStr += this.dataStore[i] + " ";
        }
        return retStr;
    }
    function empty() {//判断队列是否为空
        if (this.dataStore.length == 0) {
            return true;
        } else {
            return false;
        }
    }
    var q = new Queue();
    q.enqueue("Meredith");
    q.enqueue("Cynthia");
    q.enqueue("Jennifer");
    document.write(q.toString() + "<br />");
    q.dequeue();
    document.write(q.toString() + "<br />");
    document.write("Front of queue: " + q.front() + "<br />");
    document.write("Back of queue: " + q.back() + "<br />");
    /*测试结果：
    Meredith Cynthia Jennifer 
    Cynthia Jennifer 
    Front of queue: Cynthia
    Back of queue: Jennifer  */