fyi, I may be late to the party, but if you want to debug minified js in firefox and prefer not to wait until its integrated, I have been using this add-on[0] with success.
This feature is also available built-in in Safari and Chrome (in the dev tools, Script pane, look at the bottom buttons bar, its rightmost button is a pair of braces `{ }`. Click on that, it will reformat your source to allow for debugging, the reformatting lasts until you reload the page so it's very handy to try and debug SPA)
[0]: https://addons.mozilla.org/en-US/firefox/addon/javascript-de...