var speed=25;//速度数值越大速度越慢
demo2.innerHTML=demo1.innerHTML;
function Marquee()
{
    if(demo2.offsetWidth-demo.scrollLeft<=0)
        demo.scrollLeft-=demo1.offsetWidth;
    else
        demo.scrollLeft++;
}

function Marqueeright() {   
    if (demo.scrollLeft <= 0) {   
        demo.scrollLeft += demo2.offsetWidth;   
    }   
    else {   
        demo.scrollLeft -=2;   
    }   
}  
 
var MyMar=setInterval(Marquee,speed)
demo.onmouseover=function() 
{
    clearInterval(MyMar);
}
demo.onmouseout=function()
{
    MyMar=setInterval(Marquee,speed);
}

function GoRight() {   
    clearInterval(MyMar);   
    MyMar = setInterval(Marqueeright, speed)  ; 
}   
function GoLeft() {   
    clearInterval(MyMar);   
    MyMar = setInterval(Marquee, speed);
}