Custom JavaScript Promisify function

promisify.js

const promisify = f => (...args) => 
        new Promise((resolve, reject) => {
            f(...args, (err, res) => {
                if(err) {
                    return reject(err);
                }
                return resolve(res);
            });
        });

Variant 1 - use Node.js util

const util = require('util');
const funcAsync = util.promisify(funcCallback);

Variant 2 - use custom function

const funcAsync = promisify(funcCallback);