ESLint becomes the most useful when you get warnings before even trying to land or get your code reviewed. You can add support to your code editor but not all editors support this so I’ve written a mercurial extension which gives you warnings any time you commit code that fails lint checks. It uses the same rules we run elsewhere. It doesn’t abort the commit, that would be annoying if you’re working on a feature branch but gives you a heads up about what needs to be fixed and where.
To install the extension add this to a hgrc file, I put it in the .hg/hgrc file of my mozilla-central clone rather than the global config.
[extensions] mozeslint = <path to clone>/tools/mercurial/eslintvalidate.py
After that anything that creates a commit, so that includes mq patches, will run any changed JS files through ESLint and show the results. If the file was already failing checks in a few places then you’ll still see those too, maybe you should fix them up too before sending your patch for review? ðŸ˜‰