You can setup eslint indent rules and try using their auto-fix feature. It will not fix all the errors. I guess indentation will be fixed.

You can do auto-fix by running eslint --fix.

Case closed! Gulp prettify IS the answer

I don't start working until code is properly indented and easily readable / properly commented haha. If nothing else, it helps me better understand what the code was intended to do because I have to read all of it.

If you can't automate it - take it 1 module / section at a time and fix it when you have nothing better to do.

It's often easy to automate, either from IDE or linter itself.

But I often use the 'annotations' feature of IntelliJ IDEA, which is like git blame, except without the option to ignore whitespace changes.

So re-formatting the entire file pretty much erases its history for practical purposes and I end up not doing it.