My polyfill implementation of Promise.all

promiseAll.js

function promiseAll (promises = []) {
    return new Promise((resolve, reject) => {
        let result = []
        let resolvedPromisesCount = 0

        const handle = (index, data) => {
            if (data instanceof Error) {
                return reject(data)
            }

            result[index] = data
            resolvedPromisesCount++

            if (promises.length === resolvedPromisesCount) {
              return resolve(result)
            }
        }
        
        const isIterable = (obj) => {
          if (obj === null || obj === undefined) {
            return false
          }

          return typeof obj[Symbol.iterator] === 'function'
        }
        
        if (!isIterable(promises)) {
            return reject(new TypeError(`${typeof promises} ${promises} is not iterable`))
        }

        if (promises?.length === 0) {
            return resolve(result)
        }
        
    
        for (const index in promises) {
            const promise = promises[index]
    
            if (promise instanceof Promise) {
                promise
                    .then(data => handle(index, data))
                    .catch(err => handle(index, err))
            } else {
                handle(index, promise)
            }
        }
    })
}