var urls;
var id;

fetch("./urls.txt").then(response => response.text()).then((data) => {
    urls=data.split("\n");
    process();
})

function process() {
    var urlParams = new URLSearchParams(window.location.search); 
    id=urlParams.get('id');

    if (!urlParams.has('id') || id.isNaN || id==0){
        id=-1;
        var ref=document.referrer.replace(/[^/]*$/, '');

        for (var i=0;i<urls.length;i++){
            if (urls[i]==ref || urls[i]+"/"==ref){
                id=i;
                break;
            }//end if
        }//next
        //console.log(document.referrer+" "+ref+" "+id);
    }else{
        id--;
    }//end if
    activate();
}//