Trying to use jquery.post

Trying to use jquery.post

I have a chrome extension that uses appendGrid which uses jquery. For that reason I already have jquery included in my popup html. It is an older version of jquery but it works so I don't want to break it.

I have been having issues with using XMLhttp to do CORs so I want to try using jquery's $.post. But I am getting $ is not defined. Now realize that you can't mix html and js in a single module in an extension. And the includes for the jquery (can't be from a CDN). The include for the background.js is definitely below the include for the jquery files.

Can someone tell me why I can't use $.post?