Event Emitter

A basic event emitter and example how to use it

function addTicket(ticket, callback) {
    insertToDb(ticket);
    sendEmail(ticket);
    sendSms(ticket);
    callback();
}

but with event we can short it with this way:

# email sent
# sms sent
# Success to buy ticket
function buyTicket(ticket, callback) {
    // insert to database
    ticketEvent.emit('inserted', ticket);
    callback();
}

asynchronus way:

# Success to buy ticket
# email sent
# sms sent
function buyTicket(ticket, callback) {
  // insert to database
  setTimeout(() => {
    ticketEvent.emit('inserted', ticket);
  });
  callback();
}