Add two promises

91.8% acceptance

Mar 2, 2026

357

Given two promises promise1 and promise2, return a new promise. promise1 and promise2 will both resolve with a number. The returned promise should resolve with the sum of the two numbers.

Solution

TypeScript

Time O(1)

Space O(1)

LeetCode

solution.ts

type P = Promise<number>;

async function addTwoPromises(promise1: P, promise2: P): P {
  const [a, b] = await Promise.all([promise1, promise2]);
  return a + b;
}

/**
 * addTwoPromises(Promise.resolve(2), Promise.resolve(2))
 *   .then(console.log); // 4
 */