understanding async generators

async_generators.ts

import * as delay from 'delay';

(<any>Symbol).asyncIterator = Symbol.asyncIterator || Symbol.for("Symbol.asyncIterator");


async function* g() {
  yield 1;
  await delay(100);
  yield* [2, 3];
  yield* (async function *() {
    await delay(100);
    yield 4;
  })();
}
async function f() {
  for await (const x of g()) {
     console.log(x);
     console.log(`---`);
  }
}
f().catch(err => console.log(`error: ${err}`));


async function* ii() {
  let idx = 0;
  yield idx++;
  await delay(100);
  yield idx++;
  yield idx++;
  yield idx++;
  return 'return';
}

async function h() {
  const gg = ii();
  console.log(await gg.next());
  console.log(await gg.next());
  console.log(await gg.next());
  console.log(await gg.next());
  console.log(await gg.next());
  console.log(await gg.next());
}

h().catch(err => console.log(`err:${err}`));

async function* kk() {
  let idx = 0;
  yield;
  idx++;
  await delay(100);
  yield;
   idx++;
  yield
   idx++;
  yield
  idx++;
  return idx;
}

async function k() {
  const gg = kk();
  let result;
  while((result = await gg.next()).done === false) {
    console.log(`k: ${JSON.stringify(result)}`);
    delay(1000);
  }
  console.log(result);
}

k().catch(err => console.log(`err:${err}`));