如果你理解栈的push()和pop()函数，那么queue只是在相反的意义上进行这些操作之一。push()的对边是unshift()， pop()的对边是shift()。 然后:

//classic stack
var stack = [];
stack.push("first"); // push inserts at the end
stack.push("second");
stack.push("last");
stack.pop(); //pop takes the "last" element

//One way to implement queue is to insert elements in the oposite sense than a stack
var queue = [];
queue.unshift("first"); //unshift inserts at the beginning
queue.unshift("second");
queue.unshift("last");
queue.pop(); //"first"

//other way to do queues is to take the elements in the oposite sense than stack
var queue = [];
queue.push("first"); //push, as in the stack inserts at the end
queue.push("second");
queue.push("last");
queue.shift(); //but shift takes the "first" element

Javascript数组shift()很慢，特别是当包含很多元素时。我知道两种方法来实现平摊O(1)复杂度的队列。

首先是使用循环缓冲区和表加倍。我以前实现过这个。你可以在这里看到我的源代码 https://github.com/kevyuu/rapid-queue

第二种方法是使用两个堆栈。这是带有两个堆栈的队列的代码

function createDoubleStackQueue() {
var that = {};
var pushContainer = [];
var popContainer = [];

function moveElementToPopContainer() {
    while (pushContainer.length !==0 ) {
        var element = pushContainer.pop();
        popContainer.push(element);
    }
}

that.push = function(element) {
    pushContainer.push(element);
};

that.shift = function() {
    if (popContainer.length === 0) {
        moveElementToPopContainer();
    }
    if (popContainer.length === 0) {
        return null;
    } else {
        return popContainer.pop();
    }
};

that.front = function() {
    if (popContainer.length === 0) {
        moveElementToPopContainer();
    }
    if (popContainer.length === 0) {
        return null;
    }
    return popContainer[popContainer.length - 1];
};

that.length = function() {
    return pushContainer.length + popContainer.length;
};

that.isEmpty = function() {
    return (pushContainer.length + popContainer.length) === 0;
};

return that;}

这是使用jsPerf进行的性能比较

CircularQueue.shift() vs Array.shift()

http://jsperf.com/rapidqueue-shift-vs-array-shift

正如你所看到的，大数据集的速度要快得多

我认为实现堆栈和队列的最干净的方法应该是使用一个允许从两端添加和删除的容器，然后限制其在一端的功能，这可以通过Javascript中的一个简单数组来完成。

//堆栈容器在封装时使用的语句

// Allow push and pop from the same end
array.push(element);
array.pop();

//封装时在队列容器中使用的语句

// Allow push and pop from different ends
array.push(element);
array.shift();

数组是Javascript中的堆栈。只需使用arr.push(x)和y = arr.pop()。

下面是用Javascript实现队列的最简单方法，对于enqueue(x)和y = dequeue()，它的平摊时间都是O(1)。它使用从插入索引到元素的映射。

function newQueue() {
    return {
        headIdx: 0,
        tailIdx: 0,
        elts: {},
        enqueue: (elt) => queue.elts[queue.tailIdx++] = elt,
        dequeue: () => {
            if (queue.headIdx == queue.tailIdx) {
                throw new Error("Queue is empty");
            }
            return queue.elts[queue.headIdx++];
        },
        size: () => queue.tailIdx - queue.headIdx,
        isEmpty: () => queue.tailIdx == queue.headIdx
    };
}

使用链表实现的队列比这种基于映射的方法更有效，使用循环缓冲区实现的队列比这种基于映射的方法更有效，但这两种数据结构的实现更复杂(特别是循环缓冲区数据结构)。

Create a pair of classes that provide the various methods that each of these data structures has (push, pop, peek, etc). Now implement the methods. If you're familiar with the concepts behind stack/queue, this should be pretty straightforward. You can implement the stack with an array, and a queue with a linked list, although there are certainly other ways to go about it. Javascript will make this easy, because it is weakly typed, so you don't even have to worry about generic types, which you'd have to do if you were implementing it in Java or C#.

  var x = 10; 
  var y = 11; 
  var Queue = new Array();
  Queue.unshift(x);
  Queue.unshift(y);

  console.log(Queue)
  // Output [11, 10]

  Queue.pop()
  console.log(Queue)
  // Output [11]