How to determine the browser of the user using PHP?

So that if the users browser is IE then the variable $alert="onbeforeunload" and if it is not IE, for example Firefox (else) then $alert="onload.

Help is much appreciated.

Thanks

Also please note that I can not install browscap.ini on my PHP server.

Solution

See if this code works for you

<?php
function detect_ie(){
    return (sizeof(explode("MSIE",$_SERVER['HTTP_USER_AGENT'])) > 1);
}

if (detect_ie())
    $event = "onbeforeunload";
else
    $event = "onload";

?>