async function* numberStream() {
  yield await Promise.resolve(1);
  yield await Promise.resolve(2);
  yield await Promise.resolve(3);
}

// Consume with for await...of
(async () => {
  for await (const num of numberStream()) {
    console.log(num); // 1, 2, 3
  }
})();

async function* fetchUsers() {
  let page = 1;
  let hasMore = true;

  while (hasMore) {
    const response = await fetch(`/api/users?page=${page}`);
    const data = await response.json();

    yield data.users;

    hasMore = data.hasMore;
    page++;
  }
}

// Usage
async function processAllUsers() {
  for await (const users of fetchUsers()) {
    for (const user of users) {
      console.log(user.name);
    }
  }
}

const asyncIterable = {
  [Symbol.asyncIterator]() {
    let count = 0;
    return {
      async next() {
        if (count < 3) {
          const value = await Promise.resolve(++count);
          return { value, done: false };
        }
        return { value: undefined, done: true };
      }
    };
  }
};

(async () => {
  for await (const num of asyncIterable) {
    console.log(num); // 1, 2, 3
  }
})();

async function* streamFile(url, chunkSize = 1024) {
  const response = await fetch(url);
  const reader = response.body.getReader();

  try {
    while (true) {
      const { done, value } = await reader.read();
      if (done) return;
      yield value;
    }
  } finally {
    reader.releaseLock();
  }
}

// Usage
async function processFile() {
  for await (const chunk of streamFile('/large-file.txt')) {
    console.log(`Received chunk: ${chunk.length} bytes`);
  }
}