How to Create API in Node.js using Express

If you are a web developer, you might have heard about Node.js and its popularity in web development. Node.js is a powerful JavaScript runtime that allows developers to build scalable and efficient web applications. In this tutorial, we will learn how to create an API in Node.js using the Express framework.

Step 1: Set up Node.js and Express

First, make sure you have Node.js and npm installed on your machine. You can download and install them from the official Node.js website. Once Node.js and npm are installed, you can create a new project folder and open a terminal in that folder.

Next, you can initialize a new Node.js project by running the following command:


npm init -y


This will create a package.json file with the default settings. Now, you can install Express by running the following command:


npm install express


Step 2: Create a Basic API

Once Express is installed, you can create a new JavaScript file (e.g., app.js) and start building your API. Here’s a basic example of how to create a simple API endpoint that returns a “Hello, World!” message:


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

app.get('/', (req, res) => {
res.send('Hello, World!');
});

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


Save the file and run it using the following command:


node app.js


Now, if you open a web browser and go to http://localhost:3000, you should see the “Hello, World!” message displayed.

Step 3: Create Custom API Endpoints

Now that you have a basic API set up, you can start creating custom API endpoints for your application. For example, you can create a new endpoint that returns a list of users:


app.get('/users', (req, res) => {
res.json([
{ id: 1, name: 'John' },
{ id: 2, name: 'Jane' },
{ id: 3, name: 'Doe' }
]);
});


You can also create endpoints for handling POST, PUT, and DELETE requests to manipulate data in your application’s backend.

Step 4: Test Your API

Once you have created your API endpoints, it’s important to test them to ensure they work as expected. You can use tools like Postman or Insomnia to send HTTP requests to your API and inspect the responses. This is also a good opportunity to handle errors and edge cases in your API.

With these basic steps, you can create a powerful API in Node.js using Express. As you continue to develop your application, you can add authentication, data validation, error handling, and other advanced features to make your API more robust and secure.