How to Build a REST API Using Node.js

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REST APIs are essential for modern web development, enabling communication between clients and servers. In this guide, you’ll learn how to build a simple REST API using Node.js. By the end of this tutorial, you’ll have a fully functional API to perform basic CRUD (Create, Read, Update, Delete) operations.

Step 1: Set Up Your Environment

Before we begin, ensure you have the following installed:

  • Node.js (LTS version recommended)
  • A text editor (e.g., Visual Studio Code)
  • Postman or any API testing tool

Step 2: Initialize a Node.js Project

Create a new folder for your project and initialize a Node.js application:

mkdir rest-api-nodejs
cd rest-api-nodejs
npm init -y

This will generate a package.json file for your project.

Step 3: Install Required Dependencies

Install the following packages:

npm install express body-parser
  • Express: A minimal Node.js framework for building APIs.
  • Body-parser: Middleware to handle JSON payloads.

Step 4: Create the API

Create a file named index.js and add the following code:

const express = require('express');
const bodyParser = require('body-parser');
const app = express();
const PORT = 3000;


// Middleware
app.use(bodyParser.json());


// Sample data
let items = [
    { id: 1, name: 'Item 1' },
    { id: 2, name: 'Item 2' }
];


// Get all items
app.get('/api/items', (req, res) => {
    res.json(items);
});


// Get a single item by ID
app.get('/api/items/:id', (req, res) => {
    const item = items.find(i => i.id === parseInt(req.params.id));
    if (!item) return res.status(404).send('Item not found');
    res.json(item);
});


// Add a new item
app.post('/api/items', (req, res) => {
    const newItem = {
        id: items.length + 1,
        name: req.body.name
    };
    items.push(newItem);
    res.status(201).json(newItem);
});


// Update an item
app.put('/api/items/:id', (req, res) => {
    const item = items.find(i => i.id === parseInt(req.params.id));
    if (!item) return res.status(404).send('Item not found');
    item.name = req.body.name;
    res.json(item);
});


// Delete an item
app.delete('/api/items/:id', (req, res) => {
    const itemIndex = items.findIndex(i => i.id === parseInt(req.params.id));
    if (itemIndex === -1) return res.status(404).send('Item not found');
    items.splice(itemIndex, 1);
    res.status(204).send();
});


// Start the server
app.listen(PORT, () => {
    console.log(`Server is running on http://localhost:${PORT}`);
});

Step 5: Test Your API

Start your server by running:

node index.js

Use Postman or your browser to test the endpoints:

  • GET /api/items: Retrieve all items.
  • GET /api/items/:id: Retrieve a single item by ID.
  • POST /api/items: Add a new item.
  • PUT /api/items/:id: Update an existing item.
  • DELETE /api/items/:id: Delete an item by ID.

Conclusion

Congratulations! You’ve built a simple REST API using Node.js. From here, you can expand your API to include authentication, connect it to a database, or deploy it to a cloud platform.

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