A simple way to approach routing in express.js

models.js

// This file should be in routes/models.js

const routes = require('express').Router();
const data = require('../data.json');

routes.get('/', (req, res) => {
  res.status(200).json(data.models);
});

routes.get('/:modelId', (req, res) => {
  const modelId = req.params.modelId * 1;
  const model = data.models.find(m => m.id === modelId);

  res.status(200).json({ model });

});

module.exports = routes;

server.js

'use strict';

const express = require('express');

// We don't need the .js
const models = require('./routes/models');

const PORT = 8080;
const HOST = '0.0.0.0';

const app = express();

// Here every route method is available: /models, /models/:modelId
app.use('/models', models);

app.listen(PORT, HOST);

console.log(`Running on http://${HOST}:${PORT}`);