/*--------------双向Queue类的定义和测试代码----------------*/function Queue(){        this.dataStore = [];        this.enqueueFront = enqueueFront;        this.enqueueBack = enqueueBack;        this.dequeueFront = dequeueFront;        this.dequeueBack = dequeueBack;        this.front = front;        this.back = back;        this.toString = toString;        this.empty = empty;}//尾部入队，就是在数组的末尾添加一个元素function enqueueBack(element){    this.dataStore.push(element);}//头部入队，就是在数组的头部添加一个元素function enqueueFront(element){    this.dataStore.splice(0,0,element);}//尾部出队，就是删除数组的最后一个元素function dequeueBack(){    return this.dataStore.splice(this.dataStore.length-1, 1);}//出队，就是删除数组的第一个元素function dequeueFront(){    return this.dataStore.shift();}//取出数组的第一个元素function front(){    return this.dataStore[0];}//取出数组的最后一个元素function back(){    return this.dataStore[this.dataStore.length-1];}function toString(){    var retStr = "";    for (var i=0; i<this.dataStore.length; ++i) {        retStr += this.dataStore[i] + "&nbsp;"    }    return retStr;}//判断数组是否为空function empty(){    if(this.dataStore.length == 0){        return true;    }else{        return false;    }    }//返回数组中元素的个数function count(){    return this.dataStore.length;}var q = new Queue();q.enqueueFront("1");q.enqueueFront("2");q.enqueueBack("3");q.enqueueBack("4");document.write(q.toString());document.write(‘<br>‘);q.dequeueFront();document.write(q.toString());document.write(‘<br>‘);q.dequeueBack();document.write(q.toString());document.write(‘<br>‘);document.write(‘<br>‘);

/*---------------------------判断字符串是否是回文-------------------------*/function isPalindrome(str){    var queue = new Queue();    for (var i=0; i<str.length; i++) {        queue.enqueueFront(str[i]);    }        var newStr = "";    while (!queue.empty()){        newStr += queue.dequeueFront();    }        document.write(newStr);    document.write(‘<br>‘);    if(str == newStr){        document.writeln(str + " 是回文");    }else{        document.writeln(str + " 不是回文");    }}isPalindrome("racecar");document.write(‘<br>‘);isPalindrome("helloword");