Function isRejected

Checks if a promise result is rejected. Can be used as a type guard to narrow the type of the result to PromiseRejectedResult.

const rejected = new Promise((_, reject) => setTimeout(() => reject(new Error('fail')), 1000));
const result = await settled(rejected);
console.log(isRejected(result)); // true

const results = await Promise.allSettled([
  Promise.resolve('done'),
  Promise.reject(new Error('fail')),
]);
console.log(results.filter(isRejected)); // [{ status: 'rejected', reason: Error('fail') }]
console.log(results.filter(isFulfilled)); // [{ status: 'fulfilled', value: 'done' }]
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