var speed=20
demo2.innerHTML=demo1.innerHTML	//克隆demo1为demo2
function Marquee(){
if(demo2.offsetWidth-demo.scrollLeft<=0)	//当滚动至demo1与demo2交界时
demo.scrollLeft-=demo1.offsetWidth		//demo跳到最顶端
else{
demo.scrollLeft++
}
}
var MyMar=setInterval(Marquee,speed)	//设置定时器
demo.onmouseover=function() {clearInterval(MyMar)}//鼠标移上时清除定时器达到滚动停止的目的
demo.onmouseout=function() {MyMar=setInterval(Marquee,speed)}//鼠标移开时重设定时器