Set cookie on multiple domains with PHP or JavaScript

Question

I have 3 domains that are themed the same. If somebody chooses a different theme, I want it to propagate across all 3 domains so their experience stays the same.

I w

Answer 1

Do what Google is doing. Yes, Google is doing this same trick to login the user to YouTube and other Google services which are on different domains.

Create a PHP file that sets the cookie on all 3 domains. Then on the domain where the theme is going to set, create a HTML file that would load the PHP file that sets cookie on the other 2 domains. Example:

   
   
      
Please wait.....
      
      
   

Then add an onload callback on body tag. The document will only load when the images completely load that is when cookies are set on the other 2 domains. Onload Callback :

setcookie.php

We set the cookies on the other domains using a PHP file like this :

Now cookies are set on the three domains.

Source - My Blog