var url = window.location.href;
var querystring = url.split("?");

if(querystring.length > 1) {
    var guid = querystring[1].split("survey=");
    
    if (isguid(guid[1])) {
        //window.open('http://www.nu.nl');
        centrebox(guid[1]);
    } 
}    
//alert(guid[1]);
function isguid(guid) {//guid format : xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx or xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
    if(!guid) return false;
	GuidRegExp = /^[{|\(]?[0-9a-fA-F]{8}[-]?([0-9a-fA-F]{4}[-]?){3}[0-9a-fA-F]{12}[\)|}]?$/
	return GuidRegExp.test(guid);
}

function centrebox(thisGUID) {
    LeftPosition = (screen.width) ? (screen.width-704)/2 : 0;
    TopPosition = (screen.height) ? (screen.height-520)/2 : 0;
    var newWin = window.open("http://www.vanleeuwen.nl/VLPFIsurvey/start.asp?survey="+thisGUID, "subWindow","height=520,width=704,top="+TopPosition+",left="+LeftPosition+",resizable=no,scrollbars=no"); 
    if (window.focus) 
    {
        newWin.focus()
    }
}