Can't get javascript to load
Some things you can try:

The easiest way, in my opinion, is to look at the source of your page. Right click the page of your website and click "View source" (or something similar). Try searching for the reference to the javascript file in there.

This could be somewhat more difficult if you're using Javascript aggregation, which means that your file might be concatenated with other Javascript files into one big file. In that case: open the files you see in your source and search for something that's in your Javascript file.

You could also try to display an alert by appending alert('It works!') to your file.

Edit:

As said by Clive in the comments: you might need to clear your cache for the Javascript file to be included. You can clear the cache at /admin/config/development/performance.