JavaScript Generators and Async JavaScript Generators

generators-and-async-generators.js

const sleep = secs => new Promise(done => setTimeout(done, secs * 1000));

function* myGenerator() {
  const array = [1, 2];

  while (array.length) {
    yield array.shift();
  }
}

const iterable = {
  [Symbol.iterator]: myGenerator
};

async function* asyncGenerator() {
  const array = [() => sleep(2).then(() => 1), () => sleep(2).then(() => 2)];
  while (array.length) {
    yield await array.shift()();
  }
}

const asyncIterable = {
  [Symbol.asyncIterator]: asyncGenerator
};

for (let item of iterable) {
  console.log('myGenerator', item);
}

(async function() {
  for await (const item of asyncIterable) {
    console.log('asyncGenerator', item);
  }
})();