This content originally appeared on DEV Community and was authored by Erasmus Kotoka
APIs are the backbone of contemporary online applications, providing smooth communication between the frontend and backend.
In this post, we'll step through constructing a basic REST API using Node.js & Express from scratch. Let’s get started! 🚀
📌 Step 1: Setup Your Node.js Project
First, verify you have Node.js installed. Then, initialize a new project:
sh Copy Edit mkdir simple-api && cd simple-api npm init -y
This produces a package.json file, which maintains dependencies.
📌 Step 2: Install Express.js
Express is a lightweight and quick framework for creating web applications in Node.js. Install it:
sh Copy Edit npm install express 📌 Step 3: Create Your Server
Create a new file server.js and add this code:
javascript Copy Edit const express = require('express'); const app = express(); const PORT = 3000;
app.get('/', (req, res) => { res.send('Hello, API! 🚀'); });
app.listen(PORT, () => { console.log(Server is operating on http://localhost:${PORT}); });
What’s Happening?
✔ express() initializes an Express app.
✔ app.get('/') handles GET queries to the root URL.
✔ app.listen(PORT) launches the server.
Run it with:
sh
Copy Edit node server. js
Visit http://localhost:3000 in your browser—you should see "Hello, API! 🚀".
📌 Step 4: Add More Routes
Let’s build routes to handle CRUD actions (Create, Read, Update, Delete). Modify server. js:
javascript Copy Edit app.use(express.json()); // Middleware to parse JSON
const users = [{ id: 1, name: 'John Doe' }] ;
// Get all users app. get('/users', (req, res) => { res.json(users); });
// Add a new user app. post('/users', (req, res) => { const newUser = { id: users.length + 1, ...req.body }; users.push(newUser); res.status(201).json(newUser); });
Now you can:
✔ GET /users → Retrieve all users
✔ POST /users → Add a new user
Test with Postman or cURL:
sh Copy Edit curl -X POST -H "Content-Type: application/json" -d '{"name": "Jane Doe"}' http://localhost:3000/users 📌 Step 5: Handling Errors
Let’s add error handling to enhance our API:
javascript Copy Edit app.use((req, res) => { res.status(404).json({ message: 'Route not found!' }); });
Now, if a user accesses an incorrect endpoint, they receive a 404 error instead of a blank answer.
📌 Step 6: Running and Testing 1️⃣ Start the server:
sh Copy Edit node server. js
2️⃣ Open http://localhost:3000/users in your browser or Postman to test.
3️⃣ Use Postman to submit a POST request to /users.
🚀 Next Steps 🔹 Add MongoDB with Mongoose for data storage. 🔹 Implement JWT authentication for security. 🔹 Deploy the API using Render, Vercel, or Heroku.
By following these instructions, you’ve constructed a completely functioning REST API using Node.js & Express! 🎉
💬 Have questions? Drop them in the comments!
#NodeJS #ExpressJS #RESTAPI #Backend #WebDevelopment
This content originally appeared on DEV Community and was authored by Erasmus Kotoka
Erasmus Kotoka | Sciencx (2025-03-02T20:00:31+00:00) 🚀 Building a Simple REST API with Node.js & Express – A Step-by-Step Guide. Retrieved from https://www.scien.cx/2025/03/02/%f0%9f%9a%80-building-a-simple-rest-api-with-node-js-express-a-step-by-step-guide/
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