Note: If you haven’t completed the Promise.all question, you should attempt that first.
The Promise.allSettled() method returns a promise that resolves after all of the given promises have either fulfilled or rejected, with an array of objects that each describes the outcome of each promise.
However, if and only if an empty iterable is passed as an argument, Promise.allSettled() returns a Promise object that has already been resolved as an empty array.
For each outcome object, a status string is present. If the status is 'fulfilled', then a value is present. If the status is 'rejected', then a reason is present. The value (or reason) reflects what value each promise was fulfilled (or rejected) with.
Source: Promise.allSettled() - JavaScript | MDN
Promise.allSettled() is frequently used when there are multiple independent asynchronous tasks and we want to know the result of each promise, regardless of whether they were fulfilled or rejected.
Let’s implement our own version of Promise.allSettled(), a promiseAllSettled function, with the difference being the function takes in an array instead of an iterable. Be sure to read the description carefully and implement accordingly!
const p0 = Promise.resolve(3);const p1 = 42;const p2 = new Promise((resolve, reject) => {
setTimeout(() => {
reject('foo'); }, 100);});await promiseAllSettled([p0, p1, p2]);// [// { status: 'fulfilled', value: 3 },// { status: 'fulfilled', value: 42 },// { status: 'rejected', reason: 'foo' },// ];
You must create a function promiseAllSettled that:
Accepts an array of values or promises.
Starts all of them in parallel.
Waits until all have either:
Returns an array of result objects in the same order as the input:
{ status: 'fulfilled', value: result }
{ status: 'rejected', reason: error }
If the array is empty → return a resolved promise with [].
This implementation mirrors the real behavior of Promise.allSettled().