2723. Add Two Promises

https://leetcode.com/problems/add-two-promises/

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

• code

var addTwoPromises = async function(promise1, promise2) {
    return promise1.then(res1 => promise2.then(res2 => res1 + res2))

    // const [res1, res2] = await Promise.all([promise1, promise2]);
    // return res1 + res2

    // return await promise1 + await promise2;

};

• code

var addTwoPromises = async function (promise1, promise2) {
  return new Promise((resolve, reject) => {
    let count = 2;
    let res = 0; 
    
    [promise1, promise2].forEach(async promise => {
      try {
        const subRes = await promise;
        res += subRes;
        count--;

        if (count === 0) {
          resolve(res);
        }
      } catch (err) {
        reject(err);
      }
    });
  });
};