With the latest update to the “Modifying Ad Code,” Google now allows publishers to make some changes to their AdSense ad code.
Google has provided code snippets to help publishers implement the following techniques with their ads:
Responsive design: Create a single webpage that will adapt to the device on which it’s being viewed - however, the code snippet will not accommodate screen orientation changes
A/B testing: Run a test by creating multiple versions of a page, and compare user behavior to see which page is the most effective
Setting custom channels dynamically: Track performance of segments of users, sections of your site, or other behavior to maximize ad and user experience
Ad tag minification: Enable your site pages to load faster by reducing the amount of data to be transferred