yielding array of promises

experience.js

'use strict';
const fs = require('fs');
const co = require('co');

const files = ['./plan.md', './karma.conf.js', './package.json', './LICENSE'];

function checkFile(file) {
  return new Promise((fulfill, reject) => {
    console.log('checking file', file);
    fs.stat(file, (error) => {
      console.log('file checked', file);
      if (error) {
        return reject(error);
      }
      fulfill();
    });
  });
}

Array.prototype.mapIterable = function* mapIterable(map) {
  for (var i = 0; i < this.length; i++) {
    yield map(this[i]);
  }
};

co(function* main() {
  console.log('1 - with Promise.all');
  yield Promise.all(files.map(checkFile));

  console.log('');
  console.log('2 - yielding checks with yield*');
  yield* files.map(checkFile);

  console.log('');
  console.log('3 - yielding each check in for...of');
  for (const file of files) {
    yield checkFile(file);
  }

  console.log('');
  console.log('4 - yielding each checks with mapIterable');
  yield* files.mapIterable(checkFile);

  console.log('');
  console.log('the end');
});

result.out

1 - with Promise.all
checking file ./plan.md
checking file ./karma.conf.js
checking file ./package.json
checking file ./LICENSE
file checked ./plan.md
file checked ./package.json
file checked ./karma.conf.js
file checked ./LICENSE

2 - yielding checks with yield*
checking file ./plan.md
checking file ./karma.conf.js
checking file ./package.json
checking file ./LICENSE
file checked ./plan.md
file checked ./karma.conf.js
file checked ./package.json
file checked ./LICENSE

3 - yielding each check in for...of
checking file ./plan.md
file checked ./plan.md
checking file ./karma.conf.js
file checked ./karma.conf.js
checking file ./package.json
file checked ./package.json
checking file ./LICENSE
file checked ./LICENSE

4 - yielding each checks with mapIterable
checking file ./plan.md
file checked ./plan.md
checking file ./karma.conf.js
file checked ./karma.conf.js
checking file ./package.json
file checked ./package.json
checking file ./LICENSE
file checked ./LICENSE

the end