In the Chrome Dev Tools, it's possible to save changed CSS and JavaScript files from the Sources panel, and see what changes (diffs) have been made to those files.
For example:
-
Open a JavaScript or CSS file in the Sources panel.
-
Click in the source.
-
Make changes.
-
Press Command-S or Ctrl-S to save changes.
-
Right click on the source code (or in the Sources panel sources tree) and select Local modifications to view versioning.
-
Right-click, select Save As..., and choose a location on disk to save the file. Subsequent saves will save to this location.