[javascript] Is it possible to import modules from all files in a directory, using a wildcard?

Great gugly muglys! This was harder than it needed to be.

Export one flat default

This is a great opportunity to use spread (... in { ...Matters, ...Contacts } below:

// imports/collections/Matters.js
export default {           // default export
  hello: 'World',
  something: 'important',
};

// imports/collections/Contacts.js
export default {           // default export
  hello: 'Moon',
  email: '[email protected]',
};

// imports/collections/index.js
import Matters from './Matters';      // import default export as var 'Matters'
import Contacts from './Contacts';

export default {  // default export
  ...Matters,     // spread Matters, overwriting previous properties
  ...Contacts,    // spread Contacts, overwriting previosu properties
};

// imports/test.js
import collections from './collections';  // import default export as 'collections'

console.log(collections);

Then, to run babel compiled code from the command line (from project root /):

$ npm install --save-dev @babel/core @babel/cli @babel/preset-env @babel/node 
(trimmed)

$ npx babel-node --presets @babel/preset-env imports/test.js 
{ hello: 'Moon',
  something: 'important',
  email: '[email protected]' }

Export one tree-like default

If you'd prefer to not overwrite properties, change:

// imports/collections/index.js
import Matters from './Matters';     // import default as 'Matters'
import Contacts from './Contacts';

export default {   // export default
  Matters,
  Contacts,
};

And the output will be:

$ npx babel-node --presets @babel/preset-env imports/test.js
{ Matters: { hello: 'World', something: 'important' },
  Contacts: { hello: 'Moon', email: '[email protected]' } }

Export multiple named exports w/ no default

If you're dedicated to DRY, the syntax on the imports changes as well:

// imports/collections/index.js

// export default as named export 'Matters'
export { default as Matters } from './Matters';  
export { default as Contacts } from './Contacts'; 

This creates 2 named exports w/ no default export. Then change:

// imports/test.js
import { Matters, Contacts } from './collections';

console.log(Matters, Contacts);

And the output:

$ npx babel-node --presets @babel/preset-env imports/test.js
{ hello: 'World', something: 'important' } { hello: 'Moon', email: '[email protected]' }

Import all named exports

// imports/collections/index.js

// export default as named export 'Matters'
export { default as Matters } from './Matters';
export { default as Contacts } from './Contacts';

// imports/test.js

// Import all named exports as 'collections'
import * as collections from './collections';

console.log(collections);  // interesting output
console.log(collections.Matters, collections.Contacts);

Notice the destructuring import { Matters, Contacts } from './collections'; in the previous example.

$ npx babel-node --presets @babel/preset-env imports/test.js
{ Matters: [Getter], Contacts: [Getter] }
{ hello: 'World', something: 'important' } { hello: 'Moon', email: '[email protected]' }

In practice

Given these source files:

/myLib/thingA.js
/myLib/thingB.js
/myLib/thingC.js

Creating a /myLib/index.js to bundle up all the files defeats the purpose of import/export. It would be easier to make everything global in the first place, than to make everything global via import/export via index.js "wrapper files".

If you want a particular file, import thingA from './myLib/thingA'; in your own projects.

Creating a "wrapper file" with exports for the module only makes sense if you're packaging for npm or on a multi-year multi-team project.

Made it this far? See the docs for more details.

Also, yay for Stackoverflow finally supporting three `s as code fence markup.