You're talking about source mapping I believe. I've only used it in Chrome but I've heard only Chrome has it as good as it has it. Honestly, it's a lifesaver if you're doing frontend stuff (and you're not one of those people who poo-poo's debuggers).
There was a post recently about some CS OG who stated at some point that print statements was all you needed and using a debugger was counter-productive to your understanding of the code.
