2721. Execute asynchronous functions in parallel
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```javascript []
/**
 * @param {Array<Function>} functions
 * @return {Promise<any>}
 */
var promiseAll = function(functions) {
    return new Promise((resolve,reject) => {
        let res = Array(functions.length)
        let waitingFor = functions.length

        for(let i=0;i<functions.length;i++){
            functions[i]().then((result) =>
            {
                res[i] = result
                waitingFor--
                if(waitingFor === 0) resolve(res)
            }).catch(reject)
        }
    })
};

/**
 * const promise = promiseAll([() => new Promise(res => res(42))])
 * promise.then(console.log); // [42]
 */
```
['JavaScript']