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high number of "dotfiles" stored in the root directory of the projects

I agree, but in my case I don't care because they aren't visibile by default (Vim or whatever).

if you setup a custom directory to store all of your dotfiles, wouldn't be the same issue? Could you tell use more about your use case.

So, if I have a config directory, I can put all the config files there, and keep the root of the directory clean and easy to read.

If I have everything in the root directory, there will be a lot of configuration files put there, along with the structure of the repository and its folders (with maybe a config directory with all the configurations like webpack, rollup etc)

Example:
https://github.com/ReactTraining/react-router

As you can see, they have 8 config files in the root folder, along with the README, CONTRIBUTING etc. It would be much easier to read if they could put all the config files in a given folder, and leave in the root directory just the folders plus the various .md files (that help the onboarding of the new contributors)

Edit in reply to your edit:
For sure, dotfiles are hidden by Finder, Nautilus and major *unix file explorers, but most of the IDEs, GitHub, and text editors will (correctly) show them. I'm not sure about you, but I rarely open a project folder with Finder, I usually open it directly with Atom (and, first, I see the repository on GitHub)

It would be awesome to have a such common pattern!

There are some project which aren't using "dotfiles". I think we could extend this to CONFIG_PATH.

/cc @hzoo What do you think about this for Babel?

@FezVrasta I looked at your discussion for this in eslint. Do you still want it for Babel or can I close this?

I would suggest you to store your Babel configuration in your package.json.

I still hope to get something like what I propose in the most common libraries.

If not an environment variable, maybe a variable inside the package.json that points to the folder where the config is stored. Or something similar.

I don't see package.json the right place where to put this kind of configuration, and the reasons of the maintainer of ESlint don't seem valid to me. One can't just reject to improve the way the configuration is managed simply because it would be too difficult to do.

Here is the documentation: https://babeljs.io/docs/usage/babelrc/#use-via-package-json

@xtuc yup I'm aware of this option, I just don't think that it makes sense to use package.json (used to configure the package dependencies) as a "multi purpose / I do all the things" file.

Especially because as you can see, adding a behavior like the one I'm suggesting is just few lines of code.

I think we are going to defer doing this - not a common thing to do at the moment, but thanks for the PR!