Tell me about Promise: statuses, static methods (all, allSettled, any, race).

Promise is an object in JavaScript that represents the result of an asynchronous operation, which may be available now, later, or never.

Promise statuses:

• pending — initial state, operation not yet completed.
• fulfilled — operation successfully completed, result is available.
• rejected — operation finished with an error.

Static methods of Promise:

• Promise.all(iterable) — takes an array (or other iterable) of promises and returns a new promise that:

  • resolves when all promises in the array are fulfilled,
  • or rejects if any promise is rejected.

• Promise.allSettled(iterable) — returns a promise that resolves when all promises have settled (regardless of outcome), and returns an array of objects with the results of each promise (status and value or reason).

• Promise.any(iterable) — returns a promise that resolves as soon as any of the promises fulfills. If all promises are rejected, it returns an AggregateError.

• Promise.race(iterable) — returns a promise that settles as soon as the first promise in the array settles (fulfilled or rejected).

Example of using Promise.all:

const p1 = Promise.resolve(1);
const p2 = Promise.resolve(2);
const p3 = Promise.resolve(3);

Promise.all([p1, p2, p3])
  .then(values => console.log(values)) // [1, 2, 3]
  .catch(error => console.error(error));