var speed=25; //数字越大速度越慢 
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)
	};