栈，队列 in JavaScript

// 在JavaScript里面，已经拥有push ,pop,shift,unshift的功能，虽然栈和队列不难，然而，直接用太过简单。

// 队列
function Queue() {
    var arr = [];
    var size = 0;

    var push = function(num) {
        arr[size] = num;
        size++;
    };
    var shift = function() {
        var ret = arr[0];
        for (var i = size-1;i>0;i--){
            arr[i-1] = arr[i];
        }
        size--;
        arr.length = size; // arr[size] = null;
        return ret;
    };
    var peek = function() {
        return arr[size-1];
    };

    var isEmpty = function() {
        if(size === 0) {
            return true;
        }
            return false;
    };

    return {
        shift: shift,
        push: push,
        peek: peek,
        isEmpty: isEmpty
    };
};
var qu = new Queue();

 

// 栈
function Stock(num) {
    var arr = [];
    var size = 0;

    this.push = function(num) {
        arr[size] = num;
        size++;
    }
    this.pop = function() {
        var ret = arr[--size];
        arr[size] = null;
        return ret;
    }
    this.peek = function() {
        return arr[size-1];
    };

    this.isEmpty = function() {
        if(size === 0) {
            return true;
        }
            return false;
    };
    this.getSize = function() {
        return size;
    }
};
var st = new Stock();