@babel/cli: default the src/out directory

[hzoo]

https://babeljs.io/docs/usage/cli/#compile-directories

I think we can default babel without any arguments to be babel src --out-dir lib (default to the src/ directory and output to lib or dist?), I guess we may need to check existence and all that?

Probably a check around here?

babel/packages/babel-cli/src/babel/index.js

Line 181 in 47ce7e7

let filenames = commander.args.reduce(function(globbed, input) {

This is just so if you want to do something in package.json like "build": "babel src -d lib", you can do "build": "babel" instead.

Can look to other tools that do this kind of thing as well.

aside: we should add some better error messages around this kind of thing, like if a config isn't found, etc.

like in https://github.com/developit/microbundle, @developit

EDIT: Comment below if you are going to work on this

[Andarist]

lib is a good default for me

[rajasekarm]

+1 for lib

[xtuc]

babel --out-dir mydist could still be possible? The src is by default if you don't specify it.

[hzoo]

You can do whatever you want with the flags, this is just so babel does what people usually expect.

This + #6027 for cli should mean you just have to do babel

[mAAdhaTTah]

FWIW, Webpack appears to be defaulting to dist in Webpack 4. Might be a plus to align Babel w/ Webpack on that.

[hzoo]

Hmm I thought the convention is lib for libraries, and also what we currently do it babel, and dist for apps? not sure

[developit]

Might be worth inspecting what the user has in their package.json "main" field - it should give the directory you're looking to output to, right? I believe microbundle and preact-cli use the existence of a src directory though, that part is fine just using auto-detection.

[hzoo]

Ok so could look to the main field folder otherwise default to lib or dist?

[iansu]

I’m interested in doing this if it’s still up for grabs.

[hzoo]

Yeah go for it @iansu 👍

[iansu]

As I understand it the basic algorithm will be:

1. Try to get the output dir from main
2. If not found check for lib or dist (in which order?)
3. If not found default to lib or dist (which one?)

The big question is, what's the default lib or dist?

[hzoo]

Yeah, I was thinking lib as default. I know dist it is for webpack but this is also for cli which is used for a library? Since it's probably npmignored I don't know if we can check the folder from init?

[iansu]

That logic makes sense to me. I'll use lib as the default.

[nicolo-ribaudo]

Since it's probably npmignored

We can check .npmignore/.gitignore

[alvaropinot]

@nicolo-ribaudo that might add some "magic" difficult to reason about by the final user, don't you think?

[iansu]

I have an initial implementation of this here: #7966

It works but there are still some things to do like updating tests and documentation. Feedback welcome.