What is Promise.allSettled in JavaScript?

Can you explain what Promise.allSettled does in JavaScript?

Sure! Promise.allSettled is a method that takes an array of promises and returns a single promise that resolves when all of the promises have either resolved or rejected.

What does the returned promise look like?

The returned promise resolves to an array of objects, each representing the outcome of each promise. Each object has a 'status' property that can be 'fulfilled' or 'rejected', and a 'value' or 'reason' property depending on the outcome.

Can you give me an example of how to use it?

Absolutely! Here's a simple example:

const promise1 = Promise.resolve(3);
const promise2 = new Promise((resolve, reject) => setTimeout(reject, 100, 'error'));

Promise.allSettled([promise1, promise2]).then((results) => {
  console.log(results);
});

This will log an array with the results of both promises.

What happens if all promises are rejected?

If all promises are rejected, Promise.allSettled will still resolve, returning an array where each object has a 'status' of 'rejected' and the corresponding 'reason' for each failure.