关于前端:jquery-操作栈

最近应用前端操作栈记录操作event事件;栈是一种LIFO（Last-In-First-Out）的数据结构，即最先增加到容器中的我的项目最早被移出。这种数据结构能够限度插入和删除我的项目。而栈中项的插入和移出只会产生在栈的顶部。stack[]提供push()和pop()办法，用来实现相似栈的行为。
1、先上实例

function Stack() {    this.stack = [];    this.actionIndex = 0;}Stack.prototype.exec = function (action) {    action.exec();    this.stack[this.actionIndex++] = action;    this.stack.length = this.actionIndex;    return this;};Stack.prototype.redo = function () {    if (this.canRedo()) {        this.stack[this.actionIndex++].exec();    }    return this;};Stack.prototype.undo = function () {    if (this.canUndo()) {        this.stack[--this.actionIndex].undo();    }};Stack.prototype.canRedo = function(){    return this.actionIndex < this.stack.length;};Stack.prototype.canUndo = function(){    return this.actionIndex > 0;};function BaseAction(target, newValue,opts){    this.target = target;    this.newValue = newValue;    this.oldValue = this._get();}BaseAction.extend = function(setter,getter){    function Action(){        BaseAction.apply(this,arguments);       }    Action.prototype = BaseAction.prototype;    Action.prototype.constructor = Action;    Action.prototype._set = setter;    if(getter){        Action.prototype._get = getter;    }    return Action;};

2、应用事件办法将两个字符串推入到数组的开端，并将返回的后果保留在变量index中。用index记录栈的存取地位，