callback example

app.js

const app = {
  get: (route, cb) => {
    console.log('sending user to this route:' + route);
    const req = {
      user: 'Doug'
    };
    const res = {
      author: 'Annie',
      sendData: (data) => {
        console.log('sending this data -> ' + JSON.stringify(data))
      }
    };

    cb(req, res);
  }
};


app.get('/user', (req, res) => {
  res.sendData('the user is -> ' + req.user);
})