Able to help a newcomer?

Hi all,

I am currently learning my way into chrome extensions (basic CSS & Java) for my graduation project. I am in the mids of coding a budget extension from the tutorials from Codevolution but cannot seem to make it work...

I keep on receiving the anonymous function error message...

Uncaught ReferenceError: $ is not defined

Can someone give a tip or some help?

Thanks!

~ Jan