promise-callback.js

const callbackFunc = (name, callback) => {
    setTimeout(() => {
        return callback(name + '123');
    }, 3000);
}

const qCallbackFunc = (name) => {
    return new Promise((resolve, reject) => {
        callbackFunc(name, (result) => {
            console.log(result); 
            resolve(result);
        })
    })
}

let arr = ['Jonathan', 'Auro', 'Fernando'];
let i = 0;
let len = arr.length;
let promises = [];

for(; i<len; i++) {
    promises.push(qCallbackFunc(arr[i]))
}

Promise.all(promises).then(() => {
    console.log('finished all callbacks!');
})