Promise all function replacement

promise_all.js

function promiseAll(promises, results = []) {
    return new Promise((resolve, reject) => {
        const results = [];

        if (!promises.length) {
            return resolve(results);
        }

        let pendingPromises = promises.length;

        promises.forEach((promise, index) => {
            promise
                .then(result => {
                    results[index] = result;
                    pendingPromises -= 1;
                    if (pendingPromises === 0) {
                        return resolve(results);
                    }
                })
                .catch(err => reject(err));
        });
    });
}

function promise(fail = false) {
    return new Promise((resolve, reject) => {
        if (fail) {
            return reject('error!');
        }
        return resolve('ok');
    });
}

promiseAll([promise(), promise(true)])
    .then(result => console.log(result))
    .catch(err => console.log(err));