Mozilla and WebKit to support Source Maps

Support for debugging minified JavaScript on the way

Source Maps will streamline the debugging process

The tedious process of debugging and setting break points in minified JavaScript is set to become a lot easier as Mozilla and WebKit are both working to support Source Maps.

A Mozilla spokesperson told us: "Often, the JavaScript running on a web page is not the same as the original code that the programmer wrote. Sometimes it has been "minified" for quick downloading, or run through a compiler like CoffeeScript. With Source Maps, errors that come up in JavaScript are displayed with the line of the developer's original code rather than the final, generated JavaScript being run by the browser. Source Maps remove a step from the JavaScript debugging process. To fix a bug, developers will no longer need to look at a line of JavaScript that the browser sees and then hunt that line down in their original source files."

There is detailed information on the progress of the Mozilla work over on the wiki at, and you can read about the WebKit work at The Mozilla document states that this feature is targeted for release in Firefox 9.

The Internet Explorer developer tools are already able to unminify minified JavaScript for debugging.