Export iterator from a module to allow iterating over asterisk imports

Question

I have an index file with multiple re-exports

// things/index.js
export { a } from 'a'
export { b } from 'b'
export { c } from 'c'

Now I want to use all the things in another file as arguments to my function.
This actually works:

import * as things from './things'

things[Symbol.iterator] = function* () {
  for (let v in this) { yield v }
}

function print(things) {
  [...things].forEach(thing => {
    console.debug('thing', thing)
  });
}

print(things)

// prints:
// thing a
// thing b
// thing c

I would like to avoid having to set an iterator this way and instead export it together with the things . Is there a way?

Answer 1

Rather than using separate named exports, consider having a single export (named or otherwise), which is an object with a , b , c properties, and has a Symbol.iterator property:

// things/index.js
import { a } from 'a'
import { b } from 'b'
import { c } from 'c'
export const things = {
  a,
  b,
  c,
  [Symbol.iterator]: function* () {
    yield a;
    yield b;
    yield c;
  }
};

Or iterate over the values (the Symbol.iterator property won't be included while iterating, since it's not enumerable):

// things/index.js
import { a } from 'a'
import { b } from 'b'
import { c } from 'c'
export const things = {
  a,
  b,
  c,
  [Symbol.iterator]: function* () {
    yield* Object.values(this);
  }
};