// monsters.js
const express = require('express');
const monstersRouter = express.Router();
 
const monsters = {
  '1': {
    name: 'godzilla',
    age: 250000000
  },
  '2': {
    Name: 'manticore',
    age: 21
  }
}
 
monstersRouter.get('/:id', (req, res, next) => {
  const monster = monsters[req.params.id];
  if (monster) {
    res.send(monster);
  } else {
    res.status(404).send();
  }
});
 
module.exports = monstersRouter;



//// and
// main.js
const express = require('express');
const app = express();
const monstersRouter = require('./monsters.js');
 
app.use('/monsters', monstersRouter);