使用javaScript实现一个队列

1.队列是遵循先进先出（FIFO)原则的一组有序的项，队列在尾部添加元素，并从顶部移除元素，最新添加的元素必须排在队列的末尾。生活中常见的例子如排队等。

2.创建一个队列类

class Queue{
    constructor(){
        this.count = 0;//记录队列的数量
        this.lowestCount = 0;//记录当前队列头部的位置
        this.items = [];//用来存储元素。
    }
}

3.添加元素

  enqueue(element){
        this.items[this.count] = element;
        this.count++;
    }

4.删除元素（只删除队列头部）

    dequeue(){
        if(this.isEmpty()){
            return 'queue is null';
        }
        let resulte = this.items[this.lowestCount];
        delete  this.items[this.lowestCount];
        this.lowestCount++;
        return resulte;
    }

5.查看队列头部元素

    peek(){
        return this.items[this.lowestCount];
    }

6.判断队列是否为空

    isEmpty(){
        return this.count - this.lowestCount === 0;
    }

7.清除队列的元素

    clear(){
        this.count = 0;
        this.lowestCount = 0;
        this.items = [];
    }

8.查看队列的长度

 size(){
        return this.count - this.lowestCount;
    }

9.查看队列的所有内容

  toString(){
        if(this.isEmpty())return "queue is null";
        let objString = this.items[this.lowestCount];
        for(let i = this.lowestCount+1; i < this.count;i++){
            objString = `${objString},${this.items[i]}`;
        }
        return objString;
    }

10.完整代码

class Queue{
    constructor(){
        this.count = 0;//记录队列的数量
        this.lowestCount = 0;//记录当前队列顶部的位置
        this.items = [];//用来存储元素。
    }
    enqueue(element){
        this.items[this.count] = element;
        this.count++;
    }
    dequeue(){
        if(this.isEmpty()){
            return 'queue is null';
        }
        let resulte = this.items[this.lowestCount];
        delete  this.items[this.lowestCount];
        this.lowestCount++;
        return resulte;
    }
    peek(){
        return this.items[this.lowestCount];
    }
    isEmpty(){
        return this.count - this.lowestCount === 0;
    }
    size(){
        return this.count - this.lowestCount;
    }
    clear(){
        this.count = 0;
        this.lowestCount = 0;
        this.items = [];
    }
    toString(){
        if(this.isEmpty())return "queue is null";
        let objString = this.items[this.lowestCount];
        for(let i = this.lowestCount+1; i < this.count;i++){
            objString = `${objString},${this.items[i]}`;
        }
        return objString;
    }
}

11.运行结果