谁能帮我解释下这段JAVA语句．有的地方我看不懂．

谁能帮我解释下这段JAVA语句．有的地方我看不懂．
function startmarquee(lh,speed,delay) {
var p=false;
var t;
var o=document.getElementById("marqueebox");
o.innerHTML+=o.innerHTML;
o.style.marginTop=0;
o.onmouseover=function(){p=true;}
o.onmouseout=function(){p=false;}
function start(){
t=setInterval(scrolling,speed);
if(!p) o.style.marginTop=parseInt(o.style.marginTop)-1+"px";
}
function scrolling(){
if(parseInt(o.style.marginTop)%lh!=0){
o.style.marginTop=parseInt(o.style.marginTop)-1+"px";
if(Math.abs(parseInt(o.style.marginTop))>=o.scrollHeight/2) o.style.marginTop=0;
}else{
clearInterval(t);
setTimeout(start,delay);
}
}
setTimeout(start,delay);
}
startmarquee(20,19,3000);