2723. Add Two Promises

Description

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.

Example 1:

Input: 
promise1 = new Promise(resolve => setTimeout(() => resolve(2), 20)), 
promise2 = new Promise(resolve => setTimeout(() => resolve(5), 60))
Output: 7
Explanation: The two input promises resolve with the values of 2 and 5 respectively. The returned promise should resolve with a value of 2 + 5 = 7. The time the returned promise resolves is not judged for this problem.

Example 2:

Input: 
promise1 = new Promise(resolve => setTimeout(() => resolve(10), 50)), 
promise2 = new Promise(resolve => setTimeout(() => resolve(-12), 30))
Output: -2
Explanation: The two input promises resolve with the values of 10 and -12 respectively. The returned promise should resolve with a value of 10 + -12 = -2.

Constraints:

• promise1 and promise2 are promises that resolve with a number

Solutions

Solution 1

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async function addTwoPromises(
    promise1: Promise<number>,
    promise2: Promise<number>,
): Promise<number> {
    return (await promise1) + (await promise2);
}

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

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var addTwoPromises = async function (promise1, promise2) {
    return (await promise1) + (await promise2);
};