Promise.any() takes an iterable of
Promise objects and, as soon as one of the promises in the iterable fulfills, returns a single promise that resolves with the value from that promise. If no promises in the iterable fulfill (if all of the given promises are rejected), then the returned promise is rejected with an object that is still up for debate: either an array of rejection reasons, or an
AggregateError, a new subclass of
Error that groups together individual errors. Essentially, this method is the opposite of
Promise.any() method is experimental and not fully supported by all browsers. It is currently in the TC39 Candidate stage (Stage 3).
- An already resolved
Promiseif the iterable passed is empty.
- An asynchronously resolved
Promiseif the iterable passed contains no promises.
- A pending
Promisein all other cases. This returned promise is then resolved/rejected asynchronously (as soon as the stack is empty) when any of the promises in the given iterable resolve, or if all the promises have rejected.
This method is useful for returning the first promise that fulfills. It short-circuits after a promise fulfills, so it does not wait for the other promises to complete once it finds one. Unlike
Promise.all(), which returns an array of resolved values, we only get one resolved value (assuming at least one promise resolves). This can be beneficial if we need only one promise to resolve but we do not care which one does. Also, unlike
Promise.race(), which returns the first settled value, this method returns the first resolved value. This method will ignore all rejected promises up until the first promise that resolves.
If any of the passed-in promises fulfill, the returned promise asynchronously fulfills with the value of the promise that fulfilled, whether or not the other promises have fulfilled or rejected.
- If an empty iterable is passed, then this method returns (synchronously) an already resolved promise.
- If any of the passed-in promises fulfill, or are not promises, the promise returned by
Promise.anyis fulfilled asynchronously.
If all of the passed-in promises reject,
Promise.any asynchronously rejects with one of two options (which have not yet been agreed upon): either
- an array containing all the rejection reasons of the iterable passed as the argument, or
AggregateErrorobject, which extends
Error, and contains a pointer to an array of exceptions.
|ESNext Promise.any Proposal|