Tanmay Gupta

Posted on Jun 9

Handling GET, POST, PUT, DELETE Requests in Express

#webdev #javascript #programming #api

When building APIs with Express.js, you’ll work a lot with four main types of HTTP requests:

GET – Fetch data
POST – Create new data
PUT – Update existing data
DELETE – Remove data

In this post, you’ll learn how to handle each of these request types using Express.

Project Setup (Quick Recap)

Before writing routes, make sure your Express project is set up:

mkdir express-crud-demo
cd express-crud-demo
npm init -y
npm install express

Create an index.js file:

// index.js
const express = require('express');
const app = express();

// Middleware to parse JSON
app.use(express.json());

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server running at http://localhost:${PORT}`);
});

Sample Data (In-Memory Array)

Let’s create a fake list of users for demonstration:

let users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' }
];

1. GET Request – Fetch All Users

app.get('/users', (req, res) => {
  res.json(users);
});

Try it:

GET http://localhost:3000/users

2. POST Request – Add a New User

app.post('/users', (req, res) => {
  const newUser = {
    id: users.length + 1,
    name: req.body.name
  };
  users.push(newUser);
  res.status(201).json(newUser);
});

Sample Request Body:

{
  "name": "Charlie"
}

3. PUT Request – Update a User

app.put('/users/:id', (req, res) => {
  const userId = parseInt(req.params.id);
  const user = users.find(u => u.id === userId);

  if (!user) {
    return res.status(404).json({ message: 'User not found' });
  }

  user.name = req.body.name;
  res.json(user);
});

Sample Request:

PUT http://localhost:3000/users/1

Body:

{
  "name": "Updated Alice"
}

4. DELETE Request – Remove a User

app.delete('/users/:id', (req, res) => {
  const userId = parseInt(req.params.id);
  const index = users.findIndex(u => u.id === userId);

  if (index === -1) {
    return res.status(404).json({ message: 'User not found' });
  }

  users.splice(index, 1);
  res.json({ message: 'User deleted successfully' });
});

Complete Example

Here’s the full version of index.js with all routes:

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

let users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' }
];

app.get('/users', (req, res) => {
  res.json(users);
});

app.post('/users', (req, res) => {
  const newUser = {
    id: users.length + 1,
    name: req.body.name
  };
  users.push(newUser);
  res.status(201).json(newUser);
});

app.put('/users/:id', (req, res) => {
  const userId = parseInt(req.params.id);
  const user = users.find(u => u.id === userId);
  if (!user) return res.status(404).json({ message: 'User not found' });
  user.name = req.body.name;
  res.json(user);
});

app.delete('/users/:id', (req, res) => {
  const userId = parseInt(req.params.id);
  const index = users.findIndex(u => u.id === userId);
  if (index === -1) return res.status(404).json({ message: 'User not found' });
  users.splice(index, 1);
  res.json({ message: 'User deleted successfully' });
});

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server is running at http://localhost:${PORT}`);
});

Summary

HTTP Method	Purpose	Route Example
GET	Read data	`/users`
POST	Create data	`/users`
PUT	Update data	`/users/:id`
DELETE	Delete data	`/users/:id`

With this basic CRUD setup, you're ready to build REST APIs using Express.

DEV Community