FF dev tools are on par or even better (IMO) than Chrome, but the last few versions, it seems they have changed/dropped sourcemap support so it doesn't work at all. I went back to FF a couple years ago, but now I'm disappointed that the dev tools are not working properly and will go back for dev purposes only. I hope FF gets it working. I'd file a bug, but 'sourcemap support not working' isn't exactly all that helpful. Anyway, it doesn't work on any of my apps and works fine in Chrome. I hope they fix it at some point as I think their dev tools are generally better than Chrome (esp. the console).