You can use the following code :
<!DOCTYPE html>
<html>
<body onLoad="triggerJS();">
<script>
function triggerJS(){
location.replace("http://www.google.com");
/*
location.assign("New_WebSite_Url");
//Use assign() instead of replace if you want to have the first page in the history (i.e if you want the user to be able to navigate back when New_WebSite_Url is loaded)
*/
}
</script>
</body>
</html>