Implement `customPromiseAll(promises)` that mimics `Promise.all()`.

Question

Accepted Answer

function customPromiseAll(promises) {
  return new Promise((resolve, reject) => {
    if (!Array.isArray(promises)) {
      return reject(new TypeError('Input must be an array'));
    }

const results = [];
    let resolvedCount = 0;

if (promises.length === 0) {
      return resolve([]);
    }

promises.forEach((promise, index) => {
      // Wrap non-promise values
      Promise.resolve(promise)
        .then((value) => {
          results[index] = value;
          resolvedCount++;
          if (resolvedCount === promises.length) {
            resolve(results);
          }
        })
        .catch((err) => {
          reject(err); // Reject immediately on first error
        });
    });
  });
}

//Example Usage:

const p1 = Promise.resolve(1);
const p2 = Promise.resolve(2);
const p3 = Promise.resolve(3);
const p4 = Promise.reject("Error");

customPromiseAll([p1, p2, p3])
  .then(console.log) // ➜ [1, 2, 3]
  .catch(console.error);

customPromiseAll([p1, p4, p3])
  .then(console.log)
  .catch(console.error); // ➜ "Error"

Implement `customPromiseAll(promises)` that mimics `Promise.all()`.

Scenario Questions

Follow-up Questions