<script language="javascript" type="text/javascript">
	function   chgMusic(src){  
		if (src){  
			document.getElementById('Music_div').innerHTML="<embed src='"+src+"'></embed>";
        }  
	  }
function CountTimer(totaltime,firstalerttime,obj){
	this.second;
	this.is_CountTimeProcess1_running=false;
	this.CountTimeProcess1_end=function (){
		obj.innerHTML = '<font color="#FF0000">时间到</font>';
		is_CountTimeProcess1_running=false;
	}
	var _self = this;
	this.CountTime=function(){
		this.second -= 1;
		m=Math.floor(this.second/60);   
		se=Math.round(this.second-(Math.floor(this.second/60)*60)); 
		if (this.second == 0)
		{
			chgMusic("1.wav");
			this.CountTimeProcess1_end();
			return ;
		}		
		if (this.second==firstalerttime)
		{
			chgMusic("1.wav");
		}
		if (this.second>firstalerttime)
		{
			obj.innerHTML = +m+'分'+se+'秒';
		}
		else
		{
			obj.innerHTML = '<font color="#FF0000">'+m+'分'+se+'秒</font>';
		}
		if (this.is_CountTimeProcess1_running)setTimeout(function(){_self.CountTime()},1000);
	}
	this.CountTimeProcess1_start=function (){
		if (this.is_CountTimeProcess1_running)return;
		this.is_CountTimeProcess1_running=true;
		this.second=totaltime;
		this.CountTime();		
	}
	this.CountTimeProcess1_start();
}
</script>

<input onClick="new CountTimer(91,30,document.getElementById('second'))" type="text" />
<div id="second">&nbsp;</div>

<script src="jquery-1.3.1.js" type="text/javascript"></script>
<script src="jquery.hotkeys.js" type="text/javascript"></script>
<script>
jQuery.fn.countDown = function(settings,to) {
	if(!to && to != settings.endNumber) { to = settings.startNumber; }
	this.data("CR_currentTime",to);
	var s;
	if (to<=30)s='<div style = "color:red">'+to+'秒</div>';
		else s='<div>'+to+'秒</div>';
 
	$(this).html(s).animate({"none":"none"},settings.duration,'',function() {
		if(to > settings.endNumber + 1) {
			$(this).countDown(settings,to - 1);
		}else{
			settings.callBack(this);
		}
	});		
	return this;
};
jQuery.fn.CRcountDown = function(settings) {
	settings = jQuery.extend({
		startNumber: 240,
		endNumber: 0,
		duration: 1000,
		callBack: function() { }
	}, settings);
	this.data("CR_duration",settings.duration);
	this.data("CR_endNumber",settings.endNumber);
	this.data("CR_callBack",settings.callBack);
	return this.stop().countDown(settings);
};
jQuery.fn.pause = function(settings) {
	return this.stop();
};
jQuery.fn.reStart = function() {
	return this.pause().CRcountDown({
		startNumber : this.data("CR_currentTime"),
		duration : 	this.data("CR_duration"),
		endNumber : this.data("CR_endNumber"),
		callBack : this.data("CR_callBack")
	});
};
$.hotkeys.add('a', function(){          //a键控制正方开始
	$("#test").CRcountDown({
				startNumber:240,      //正方倒计时时间
				callBack:test
			})
			.css("color","black");
});
$.hotkeys.add('s', function(){          //s键控制正方暂停
	$("#test").pause();
});
$.hotkeys.add('d', function(){          //d键控制正方恢复
	$("#test").reStart();
});
function test(){
	$("<div class=t1>时间到</div>")
			  .hide()
			  .fadeIn(1000)
			  .appendTo("body");
}
$.hotkeys.add('z', function(){          //z键控制正方开始
	$("#test2").CRcountDown({
				startNumber:240,      //反方倒计时时间
				callBack:test2
			});
});
$.hotkeys.add('c', function(){          //c键控制反方暂停
	$("#test2").pause();
});
$.hotkeys.add('x', function(){          //x键控制正方恢复
	$("#test2").reStart();
});
function test2(){
	$("<div class=t2>时间到</div>")
			  .hide()
			  .fadeIn(1000)
			  .appendTo("body");
}
</script>

<div id="test">&nbsp;</div>
<div id="test2">&nbsp;</div>