Node.js REST API Implementation

When building a REST API with Node.js, you can utilize its built-in modules like http to create a straightforward and efficient API. Below is a step-by-step guide to implement a REST API without any external libraries or database integration.

Step 1: Setting Up the Node.js Environment

1. Initialize a Node.js project
   Create a folder for your project and initialize a package.json file:

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

2. Create the Main Server File
   Create a file named server.js where the API logic will reside:

touch server.js

Step 2: Writing the Server Code

In the server.js file, start by importing the required modules and initializing the server.

const http = require('http');

// Data storage for demonstration (in-memory storage)
let data = [
    { id: 1, name: "Item 1" },
    { id: 2, name: "Item 2" },
    { id: 3, name: "Item 3" }
];

// Helper function to parse JSON request body
function parseRequestBody(req) {
    return new Promise((resolve, reject) => {
        let body = '';
        req.on('data', chunk => (body += chunk));
        req.on('end', () => {
            try {
              resolve(JSON.parse(body));
            } catch (error) {
              reject(error);
            }
        });
    });
}

// Create HTTP server
const server = http.createServer(async (req, res) => {
    const { method, url } = req;

    // Route: GET /items
    if (method === 'GET' && url === '/items') {
        res.writeHead(200, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify(data));
    }
    // Route: POST /items
    else if (method === 'POST' && url === '/items') {
        try {
            const newItem = await parseRequestBody(req);
            newItem.id = data.length ? data[data.length - 1].id + 1 : 1;
            data.push(newItem);
            res.writeHead(201, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify(newItem));
        } catch (error) {
            res.writeHead(400, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify({ error: 'Invalid JSON' }));
        }
    }
    // Route: PUT /items/:id
    else if (method === 'PUT' && url.startsWith('/items/')) {
        const id = parseInt(url.split('/')[2], 10);
        const index = data.findIndex(item => item.id === id);
        if (index === -1) {
            res.writeHead(404, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify({ error: 'Item not found' }));
            return;
        }
        try {
            const updatedItem = await parseRequestBody(req);
            data[index] = { ...data[index], ...updatedItem };
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify(data[index]));
        } catch (error) {
            res.writeHead(400, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify({ error: 'Invalid JSON' }));
        }
    }
    // Route: DELETE /items/:id
    else if (method === 'DELETE' && url.startsWith('/items/')) {
        const id = parseInt(url.split('/')[2], 10);
        const index = data.findIndex(item => item.id === id);
        if (index === -1) {
            res.writeHead(404, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify({ error: 'Item not found' }));
            return;
        }
        data.splice(index, 1);
        res.writeHead(204); // No content
        res.end();
    }
    // Route Not Found
    else {
        res.writeHead(404, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ error: 'Route not found' }));
    }
});

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

Step 3: Running the Server

Start the server using Node.js:

node server.js

Step 4: Testing the API

You can test the API endpoints using curl or Postman. Here are some example requests:

1. GET /items

curl -X GET http://localhost:3000/items

2. POST /items

curl -X POST http://localhost:3000/items -H "Content-Type: application/json" -d '{"name":"New Item"}'

3. PUT /items/:id

curl -X PUT http://localhost:3000/items/1 -H "Content-Type: application/json" -d '{"name":"Updated Item"}'

4. DELETE /items/:id

curl -X DELETE http://localhost:3000/items/1

Conclusion

This Node.js REST API implementation demonstrates a simple and efficient way to create an API using the built-in http module. While this approach is suitable for learning and small-scale applications, consider using frameworks like Express.js or adding a database for more robust projects.