window.onload = function(){

var area = document.getElementById('moocBox');

var con1 = document.getElementById('con1');

var con2 = document.getElementById('con2');

con2.innerHTML = con1.innerHTML;

function scrollUp(){

if(area.scrollTop >= area.offsetHeight){

area.scrollTop = 0;

}else{

area.scrollTop ++;

}

}

var timer = setInterval(scrollUp,50); ? //setInterval引用傳參，第一個直接寫函數(shù)名，不用加引號，第二個參數(shù)寫時間；

area.onmouseover = function(){

clearInterval(timer);

}

area.onmouseout = function(){

timer = setInterval(scrollUp,50); ?

}

}

在第九段文字到頂后，會小頓一下，感覺就是

if(area.scrollTop >= area.offsetHeight+15){

area.scrollTop = 0;

}這一段，把area.scrollTop = 0重置為0的時候頓的