Simple PHP code not working on mobile - php

Question

THis may be super basic, but I have not been able to resolve this after spending hours!
I am running PHP 7 on Ubuntu 16.1.
The PHP file is EXACTLY as follows
<?php
header("Content-type: application/javascript");
header("HTTP/1.1 200 OK");
ExpandShortLink();
function ExpandShortLink()
{
// get URL
$URL_To_Expand = $_REQUEST['url'];
// for short links, get the full links
// get full URL
$arr_URL_Header = get_headers($URL_To_Expand, 1);
$strLink = $arr_URL_Header['Location'];
//echo $URL_To_Expand;
//print_r($arr_URL_Header);
if ($strLink) {
if (is_array($strLink)) {
$Full_URL = array_pop($strLink);
} else {
$Full_URL = $strLink;
}
} else {
$Full_URL = $URL_To_Expand;
}
echo $Full_URL;
}
--> produces the url I enter as a "url" parameter on desktop. But nothing on mobile!
On some reading, I found that in sometimes PHP interprets everything after "//" as a comment and that may be happening here. But then why does it happen on mobile only? Also, andy suggestions on resolving this will be great!
Thanks much for your help,
You can see this live here
If you click this on desktop, you will see http:// example. com. However, on mobile it will return http:

Answer 1

Not sure if this qualifies as answer, but I wanted to put a note here for anyone else who may be facing a similar problem.
I was using the PHP pasted above for an ajax call. I tried using text/plain instead of application/json and now it works across all browsers and all devices (as far as I could test).
Not sure why application/javascript was causing problems on mobile chrome, but I think text/plain makes sense as I was just passing back a text string instead of a javascript.
As I said it probably is not the fully qualified answer, but hopefully it helps someone in future!