async.generator.ja.js

async function* asyncRandomNumbers() {
  // This is a web service that returns a random number
  const url = 'https://www.random.org/decimal-fractions/?num=1&dec=10&col=1&format=plain&rnd=new';

  while (true) {
    const response = await fetch(url);
    const text = await response.text();
    yield Number(text);
  }
}

var iter = asyncRandomNumbers();

iter.next()
    .then(result => console.log('success:', result.value, result.done), 
          reason => console.log('error:', reason));
// success: 0.6191637358 false

iter.return('result-value')
    .then(result => console.log('success:', result.value, result.done), 
          reason => console.log('error:', reason));
// success: result-value true

iter.throw('exception')
    .then(result => console.log('success:', result.value, result.done), 
          reason => console.log('error:', reason));
// error: exception

async function example() {
  for await (const number of asyncRandomNumbers()) {
    console.log(number);
    if (number > 0.95) break;
  }
}

async generator* asyncRandomNumbersWrapper() {
  yield* asyncRandomNumbers();
}