Click the download link to pop up the page to implement the code

<A
onclick=checkopen(this);
href="https://"
target=_blank>Open download page 1</A>
<script>
<!--
var original_url = ""
var adurl = new Array(9);
var isclick = false;
var adurl_i = 5;
adurl[0] = "https://";
adurl[1] = "http:///";
adurl[2] = "/";


function selectFrom(iFirstValue,iLastValue){
var iChoces = (iLastValue - iFirstValue) + 1;
return (() * iChoces + iFirstValue);
    }

adurl_i = selectFrom(0,2);

function checkopen(a){
if(adurl_i<9){
if(isclick==false){
original_url = ;    
= adurl[adurl_i];
     isclick = true;
     = original_url;    
     }else{
     = original_url;
    }
}
}
//-->
</script>