SOURCE

var asyncIter = { [Symbol.asyncIterator]() {
    var items = ['h', 'e', 'l', 'l', 'o'];
    return {
      next() {
        return Promise.resolve({
          done: items.length === 0,
          value: items.shift()
        });
      }
    };
  }
}; (async function() {
  for await(let i of asyncIter) {
    console.log(i);
  }
})();