How to access variable in PHP

programming
1

I am a real newbie at PHP and have, I hope, a simple question. I have found a variable with Firebug in the DOM section and would like to access it to determine if it is true or false. The variable is called isResponsive and here is a screenshot of the Firebug console and where the variable is located:

Any help in how to access this variable is very much appreciated!!

Thanks in advance,
Doug