如何实现撤销功能？js可以吗？

[czp3158]

如题

[dh20156]

简单写个参考的：

<style type="text/css">
div{border:3px solid black;padding:10px;}
</style>

<div id="x">初始值</div>

<script type="text/javascript">
//要应用command模式的对象
var box = function(dbox,svalue){
	this.value = svalue;
	this.dbox = dbox;
	this.restart = function(){//约定一个回到初始状态的方法
		this.value = svalue;
		this.dbox.innerHTML = svalue;
	};
};
box.prototype = {
	setValue:function(svalue){
		this.value = svalue;
		this.dbox.innerHTML = svalue;
	}
};
//command对象
var command = function(receiver){
	this.receiver = receiver;
	this.log = [];
	this.un_re_do = -1;
};
command.prototype = {
	query:function(cmd){
		if(!cmd||cmd.constructor!=Function){return;}
		var args = Array.prototype.slice.call(arguments,0);
		var idx = this.un_re_do+1,ll = this.log.length;
		if(ll){this.log.splice(idx,ll-idx);}
		this.log.push(args);
		this.un_re_do++;
		this.exec.apply(this,args);
	},
	exec:function(){
		var args = Array.prototype.slice.call(arguments,0);
		if(!args.length){return;}
		var cmd = args.shift();
		if(cmd.constructor!=Function){return;}
		cmd.apply(this.receiver,args);
	},
	undo:function(){
		var idx = (this.un_re_do>=0)?--this.un_re_do:-1;
		this.unredo(idx);
	},
	redo:function(){
		var idx = (this.un_re_do<this.log.length-1)?++this.un_re_do:this.un_re_do;
		this.unredo(idx);
	},
	unredo:function(idx){
		if(idx>=0){
			var cmd_step = this.log[idx];
			this.exec.apply(this,cmd_step);
		}else{
			this.receiver.restart();
		}
	}
};

var hellobox = new box(document.getElementById('x'),'初始值');
var boxCommand = new command(hellobox);

window.setTimeout(function(){boxCommand.query(hellobox.setValue,'第一次修改值！');},1000);
window.setTimeout(function(){boxCommand.undo();},2000);
window.setTimeout(function(){boxCommand.query(hellobox.setValue,'第二次修改值！');},3000);
window.setTimeout(function(){boxCommand.undo();},4000);
window.setTimeout(function(){boxCommand.redo();},5000);
window.setTimeout(function(){boxCommand.query(hellobox.setValue,'第三次修改值！');},6000);
window.setTimeout(function(){boxCommand.query(hellobox.setValue,'第四次修改值！');},7000);
window.setTimeout(function(){boxCommand.undo();},8000);
window.setTimeout(function(){boxCommand.undo();},9000);
window.setTimeout(function(){boxCommand.undo();},10000);
</script>

[czp3158]

怎么没人知道吗？？？？

[dh20156]

当然可以，参见：

Command模式-命令模式