var speed = 30;
var offsetWidth = 3;
var tab=document.getElementById("demo"); 
var tab1=document.getElementById("demo1"); 
var tab2=document.getElementById("demo2"); 
tab2.innerHTML = tab1.innerHTML;

function Marquee() {
    if(tab2.offsetWidth - tab.scrollLeft <= 0) {
            tab.scrollLeft -= tab1.offsetWidth;
    }else{
            tab.scrollLeft++;
    } 
} 

var MyMar = setInterval(Marquee, speed); 

tab.onmouseover=function() {clearInterval(MyMar)}; 
tab.onmouseout=function() {MyMar = setInterval(Marquee, speed)};