Popup window for a specific traffic source

[TFLNetwork]

Okay, so here it goes-

I am going to run a campaign on facebook to a "landing page". However, this landing page gets a ton of organic traffic.

Is it possible to have a popup occur ONLY when the traffic is coming from facebook?

If so, what is the code?

Thanks

 

[bullet-ride]

<?php
   $ref = $_SERVER['HTTP_REFERER'];
 
   if(strpos($ref,"facebook.com")){
     // Your javascript popup code goes here.
}
 ?>