ff-diff

ff-diff is a CLI to compare changes in user preference between two versions of Firefox without messing with your firefox instance.

Features:

• Compares user.js files from two specified Firefox versions
• Automatically downloads official Firefox binaries
• Highlights differences without requiring a local Firefox installation
• Detect and identify changes required in your user.js

Requirements:

• Internet connection (for downloading Firefox binaries, only for the diff command)
• node >= 20 and npm
• tar (only for the diff command)

Installation (NPM)

npm i -g ff-diff

Usage

$ ff-diff
Usage:
  ff-diff clean [--keep version1,version2] [--keep-archives] [--keep-sources]
  ff-diff diff <old-version> <new-version> [--clean-archives] [--clean-sources] [--do-not-print-in-console] [--save-output-in-file] [--compare-userjs path]
  ff-diff default-prefs [--do-not-print-in-console] [--save-output-in-file] [--firefox-path path]
  ff-diff unused-prefs-userjs path [--firefox-path path] [--force-default-profile] [--profile-path]
  ff-diff default-prefs-userjs path [--firefox-path path] [--do-not-print-in-console] [--save-output-in-file] [--force-default-profile] [--profile-path]

Options:
  -v, --version    Print version info and exit
  -h, --help       Print help

Example:

ff-diff diff 137.0 138.0

Develop

Clone this repository:

git clone https://github.com/martabal/ff-diff.git
cd ff-diff
npm ci
npm run ff-diff -- diff -h

Commands

diff

Run the comparison command:

npm run ff-diff diff <old-version> <new-version>

for example:

npm run ff-diff diff 137.0 138.0

If you use a custom user.js. You can check if some of the keys are removed/changed with the argument --compare-userjs <path_to_your_userjs>.

Note

The script may take some time to run depending on your connection speed.

Example of a generated diffs:

clean

When running the script in development mode with npm run dev, Firefox sources and binaries are saved in the current directory. In production mode (i.e., when the script is installed globally using npm i -g ff-diff), these files are stored in ~/.ff-diff.

By default, the script keep both the downloaded archives and the extracted source files. To remove them, you can run the script with the --remove-archives and/or --remove-sources arguments. If you want to use specific version you can use:

npm run ff-diff clean -- --keep <version1>,<version2>

If you want to only keep archives you can use npm run clean -- --keep <version1>,<version2> --keep-archives or npm run clean -- --keep <version1>,<version2> --keep-sources if you want to keep the sources

default-prefs

Get all the default prefs from your firefox instance. You can specify the executable path with --firefox-path path and save the output in .ff-diff/default/<version>-user.js if you add the argument --save-output-in-file.

unused-prefs-userjs

The first argument is the path to your user.js. It will detect all prefs set in your firefox instance which are not used anymore. You can specify the executable path with --firefox-path path. If you add a comment next to your user_pref() entry like // [CUSTOM PREF] or the version the pref has been removed like // [FF136-], ff-diff won't identify that entry as a default entry.

default-prefs-userjs

The first argument is the path to your user.js. It will detect all prefs set in your firefox instance which are already the defaults. You can specify the executable path with --firefox-path path. If you add a comment next to your user_pref() entry like // [DEFAULT: false] or // [DEFAULT: true FF141+] (with or without the version), ff-diff won't identify that entry as a default entry.