support all config file extensions (.js,.mjs,...)

[arlac77]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers: #3189

Description

support naming the config file *.mjs

rollup --config my.config.mjs

[codecov]

Codecov Report

Merging #3204 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3204      +/-   ##
==========================================
+ Coverage   90.63%   90.63%   +<.01%     
==========================================
  Files         167      167              
  Lines        5905     5906       +1     
  Branches     1792     1792              
==========================================
+ Hits         5352     5353       +1     
  Misses        336      336              
  Partials      217      217

Impacted Files	Coverage Δ
cli/run/loadConfigFile.ts	84% <100%> (+0.66%)	⬆️

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[lukastaegert]

Test and doc changes look good, but I wonder if we might solve similar issues once and for all by allowing every extension, see my suggestion.

[lukastaegert]

This will work nicely for '.js' and '.mjs' but not other extensions, and is slightly complicated. How about this: As we KNOW the name of the config file, how about using path.extname to extract the extension of the config file and just modify the loader for this extension?

[arlac77]

makes perfect sense

[lukastaegert]

Thanks a lot, this looks really nice now!

[jrgleason]

I am trying to use this and I am calling like...

../../node_modules/.bin/rollup -c rollup.config.mjs

import {getMJS} from "@jrg-material/build"

import pkg from './package.json';

export default [getMJS(pkg)];

but I get...

TypeError: defaultLoader is not a function
at Object.require.extensions. [as .mjs] (/Users/jackiegleason/Code/jrg-material/node_modules/rollup/dist/bin/rollup:834:17)
at Module.load (internal/modules/cjs/loader.js:1050:32)
at Function.Module._load (internal/modules/cjs/loader.js:945:14)
at Module.require (internal/modules/cjs/loader.js:1090:19)
at require (internal/modules/cjs/helpers.js:72:18)

Notice it seems to be using the cjs loader still.

[jrgleason]

looks like this does work (lerna and my node_modules is in root for dev deps)

import {getMJS} from "../../node_modules/@jrg-material/build/dist/index.mjs"

Is there a way to import without needing the relative path?