Is "yield await" redundant in JavaScript async generator functions?

Question

Promises yielded within async function* declarations seem to be automatically awaited before the iterator result is sent to the caller (source: MDN). Does this mean that yield await somePromise is redundant and yield somePromise will produce the same behavior in all cases? Or, are there exceptions to watch out for?

P.S. I thought there might be some behavioral differences related to error handling contexts and try/catch. From my experimentation though, it seems that a promise yielded in a try block will always be caught and handled within the async generator, regardless if there is an explicit await.

Answer 1

The await is quite redundant here. Using await also delays the resolve timing in the microtask queue.

Promise.resolve()
  .then(() => console.log(1))
  .then(() => console.log(2))
  .then(() => console.log(3))
  .then(() => console.log(4))
  .then(() => console.log(5));
  
(async () => {
  const func = async function*() {
    yield await Promise.resolve('yield await');
  };
  
  for await (let i of func()) {
      console.log(i);
  }
})();

Promise.resolve()
  .then(() => console.log(1))
  .then(() => console.log(2))
  .then(() => console.log(3))
  .then(() => console.log(4))
  .then(() => console.log(5));
  
(async () => {
  const func = async function*() {
    yield Promise.resolve('yield');
  };
  
  for await (let i of func()) {
      console.log(i);
  }
})();