function addloadEvent(fun){
    var olonload=window.onload;
    if(typeof window.onload!='function'){
        window.onload=fun;
    }else{
        window.onload=function(){
            olonload();
            fun();
        }
    }
}

function highlightnav(){
    if(!document.getElementsByTagName) return false;
    if(!document.getElementById) return false;
    if(!document.getElementById("nav")) return false;
    var nav=document.getElementById("nav");
    var links = nav.getElementsByTagName("a");
    for(var i=0;i<links.length;i++){
        var linkurl=links[i].getAttribute("href");
        var currenturl= window.location.href;
        if(currenturl.indexOf(linkurl)!=-1){
            links[i].className="on";
        }
    }
}
addloadEvent(highlightnav);