If you want to find a specific parameter from a specific url:
function findParam(url, param){
var check = "" + param;
if(url.search(check )>=0){
return url.substring(url.search(check )).split('&')[0].split('=')[1];
}
}
var url = "http://www.yourdomain.com/example?id=1&order_no=114&invoice_no=254";
alert(findParam(url,"order_no"));