Promise.all
will reject as soon as one of the Promises in the array rejects.
Promise.allSettled
will never reject – it will resolve once all Promises in the array have either rejected or resolved.
Their resolve values are different as well. Promise.all
will resolve to an array of each of the values that the Promises resolve to – eg [Promise.resolve(1), Promise.resolve(2)]
will turn into [1, 2]
. Promise.allSettled
will instead give you [{ status : 'fulfilled', value: 1 }, { status : 'fulfilled', value: 2 }]
.
Promise.all([Promise.resolve(1), Promise.resolve(2)])
.then(console.log);
Promise.allSettled([Promise.resolve(1), Promise.resolve(2)])
.then(console.log);
If one of the Promises rejects, the Promise.all
will reject with a value of the rejection, but Promise.allSettled
will resolve with an object of { status: 'rejected', reason: <error> }
at that place in the array.
Promise.all([Promise.reject(1), Promise.resolve(2)])
.catch((err) => {
console.log('err', err);
});
Promise.allSettled([Promise.reject(1), Promise.resolve(2)])
.then(console.log);