How can you create a simple REST API using Node.js and Express?

To create a REST API, define routes for CRUD operations and handle requests appropriately.

Example:

const express = require('express');
const app = express();
app.use(express.json());

let items = [];

app.get('/items', (req, res) => res.json(items));
app.post('/items', (req, res) => {
  items.push(req.body);
  res.status(201).json(req.body);
});
app.put('/items/:id', (req, res) => {
  const item = items[req.params.id];
  items[req.params.id] = { ...item, ...req.body };
  res.json(items[req.params.id]);
});
app.delete('/items/:id', (req, res) => {
  items.splice(req.params.id, 1);
  res.status(204).send();
});

app.listen(3000, () => console.log('API running on http://localhost:3000'));