Multi-level Return - Doesn't Give Enough Time To Set The Variable

I'm using ajax to grab a response from a PHP page, on success, the ajax sets a variable. After the line that calls the ajax function is the line the returns the variable (a global variable). Problem is, because the variable is returned right after the ajax function is fired, it doesn't give the ajax enough time to set the variable. The work around I've thought about would be using the ajax function as a variable, and returning that variable in the initial return line.

Here's some code for reference:

The function that will return the response I'm trying to collect:

The ajax code: