Placing content in a .js file
What you can do is try creating a copy of splitex.js and saving it as splitex.php.js.
Then add this line to the very top of the file:
Followed by any other PHP code you need. Just make sure when you view source of the .php.js file it's valid js.
Hope that helps!
Sorry, correction. You want to name the file with a .js.php ending, so splitex.js.php.