Faster Smarter JavaScript Debugging in Firefox DevTools

Moreover, script debugging is a hard-to-learn skill that should work in similar fashion across browsers, but isn’t consistent because of feature and UI gaps. This allows workers and their scripts to be debugged within the same Debugger panel, similarly to other modern browsers. The Source Maps project, started and maintained by Firefox, bridges the gap between minified code running in the browser and its original, human-friendly version, but the translation isn’t perfect.

Source: hacks.mozilla.org