js问题

<script language="JavaScript" type="text/JavaScript">
var imgUrl=new Array();
var imgLink=new Array();
var adNum=0;

imgUrl[1]="../pic/1.jpg";
imgLink[1]="http://192.168.0.241/index/movie.asp?id=23226";
imgUrl[2]="../pic/4.jpg";
imgLink[2]="http://192.168.0.241/index/movie.asp?id=25312";
imgUrl[3]="../pic/4.jpg";
imgLink[3]="http://192.168.0.241/index/movie.asp?id=23226";
imgUrl[4]="../pic/4.jpg";
imgLink[4]="http://192.168.0.241/index/movie.asp?id=23226";
imgUrl[5]="../pic/5.jpg";
imgLink[5]="http://192.168.0.241/index/movie.asp?id=23226";

var imgj=0;
for (imgi=1;imgi<=5;imgi++) {
 if( (imgUrl[imgi]!="") && (imgLink[imgi]!="") ) {
  imgj++;
 } else {
  break;
 }
}

 function playTran(){
  if (document.all)
   imgInit.filters.revealTrans.play();
 }

 var key=0;
 function nextAd(){
  if(adNum<imgj)adNum++ ;
  else adNum=1;
  
  if( key==0 ){
   key=1;
  } else if (document.all){
   imgInit.filters.revealTrans.Transition=23;
   imgInit.filters.revealTrans.apply();
      playTran();

  }
  document.images.imgInit.src=imgUrl[adNum];
  theTimer=setTimeout("nextAd()", 8000);
 }


 function goUrl(){
  jumpUrl=imgLink[adNum];
  jumpTarget='_blank';
  if (jumpUrl != ''){
   if (jumpTarget != '')
    window.open(jumpUrl,jumpTarget);
   else
    location.href=jumpUrl;
  }
 }
</script>
<a href="javascript:goUrl()"><img style="FILTER: revealTrans(duration=3,transition=20);" src="javascript:nextAd()" width=482 height=357 border=0  name=imgInit></a></div></td>
谁可以帮我详细的解释下这代码么。？
  js我一点不会！