$(function(){
	var oul = $('.wrap ul');
	var oulHtml = oul.html();
	oul.html(oulHtml+oulHtml)
	var timeId = null;

	var ali = $('.wrap ul li');
	var aliWidth = ali.eq(0).width();
	var aliSize = ali.size();
	var ulWidth = aliWidth*aliSize;
	oul.width(ulWidth);	//1600px
	
	var speed = 2;

	function slider(){

		if(speed<0){
			if(oul.css('left')==-ulWidth/2+'px'){
	 		oul.css('left',0);
		 	}
		 	oul.css('left','+=-2px');
		}

	 	
		if(speed>0){
			if(oul.css('left')=='0px'){
	 		oul.css('left',-ulWidth/2+'px');
		 	}
		 	oul.css('left','+='+speed+'px');
		}
	 	
	 }
	
	// setInterval()函数的作用是：每隔一段时间，执行该函数里的代码
	 timeId = setInterval(slider,30);

	$('.wrap').mouseover(function(){
		// clearInterval()函数的作用是用来清除定时器
		clearInterval(timeId);
	});

	$('.wrap').mouseout(function(){
		timeId = setInterval(slider,30);
	});


});