Express.js Routing and CRUD API for Student Management

Express.js Routing Basics

The first example sets up a simple Express.js server with static routes, a dynamic route, and a 404 handler.

const express = require('express');
const app = express();

// Route 1
app.get('/', (req, res) => {
  res.send('Home Page');
});

// Route 2
app.get('/about', (req, res) => {
  res.send('About Page');
});

// Route 3: Dynamic route
app.get('/users/:id', (req, res) => {
  res.send(`User ID: ${req.params.id}`);
});

// 404 handler: Keep it last
app.use((req, res) => {
  res.status(404).send('404 - Page Not Found');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Building a RESTful Student API

The second example implements a RESTful API for managing students, supporting all four CRUD operations.

const express = require('express');
const app = express();

app.use(express.json());

let students = [
  { id: 1, name: 'John', age: 20 },
  { id: 2, name: 'Jane', age: 22 }
];

// GET: Read all students
app.get('/students', (req, res) => {
  res.json(students);
});

// GET: Read student by ID
app.get('/students/:id', (req, res) => {
  const student = students.find(
    s => s.id === Number(req.params.id)
  );

  if (!student) {
    return res.status(404).send('Student not found');
  }

  res.json(student);
});

// POST: Create a student
app.post('/students', (req, res) => {
  const student = {
    id: students.length
      ? Math.max(...students.map(s => s.id)) + 1
      : 1,
    name: req.body.name,
    age: req.body.age
  };

  students.push(student);
  res.status(201).json(student);
});

// PUT: Update a student
app.put('/students/:id', (req, res) => {
  const student = students.find(
    s => s.id === Number(req.params.id)
  );

  if (!student) {
    return res.status(404).send('Student not found');
  }

  student.name = req.body.name ?? student.name;
  student.age = req.body.age ?? student.age;

  res.json(student);
});

// DELETE: Delete a student
app.delete('/students/:id', (req, res) => {
  const index = students.findIndex(
    s => s.id === Number(req.params.id)
  );

  if (index === -1) {
    return res.status(404).send('Student not found');
  }

  const deleted = students.splice(index, 1);
  res.json(deleted[0]);
});

// 404 handler
app.use((req, res) => {
  res.status(404).send('Route not found');
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

Key Takeaways

• Routes map HTTP methods and URL paths to handler functions.
• Dynamic parameters such as :id are read from req.params.
• The express.json() middleware parses incoming JSON request bodies.
• The 404 handler must be registered after all other routes.