var demo = document.getElementById("demo");
var demo1 = document.getElementById("demo1");
var demo2 = document.getElementById("demo2");
var speed = 30;
demo2.innerHTML = demo1.innerHTML //克隆demo1为demo2
function Marquee() {
	if (demo.scrollLeft - demo1.offsetWidth <= 0) //当滚动条向左滚动的距离小于等于demo1自身宽度时;
		demo.scrollLeft++; //滚动条向左滚动加1
	else { //当滚动条向左滚动的距离大于demo1的宽度时;
		demo.scrollLeft = 0; //滚动条回到最最左
	}
}
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