random_time.js

const promise = () => {
    const randomNum = Math.floor(Math.random() * 1000);
    console.log('created: ' + randomNum);
    return new Promise(resolve => {
        setTimeout(
            resolve.bind(this, randomNum),
            randomNum
        );
    });
}

const show = value => {
    console.log(value);
    return value;
}

const calc = value => {
    console.log('Stopped');
    console.log(Date.now() - startTime + 'ms');
}

console.log('Started');
const startTime = Date.now();
console.log('Creating Promises');
const promises = [promise(), promise(), promise()];
console.log('Promises Created');
Promise.all(promises).then(show).then(calc);