List all js global variables used by site (not all defined!)

In Chrome, go to Dev tools and open the console.
Then type in the following:

Object.keys( window );

This will give you an Array of all the global variables.

EDIT

After searching on Google a bit, I found a way. You will need firefox and the jslinter addon.

Once setup, open jslinter and go to Options->check everything on the left column except “tolerate unused parameters”.

Then run jslinter on the webpage and scroll down in the results. You will have a list of unused variables (global and then local to each function).

Now run Object.keys(window); in the console and compare the results from both to figure out which ones are used.