Getting Started with the MERN Stack: A Beginner’s Guide

Introduction: The MERN stack is a popular JavaScript stack used for building full-stack web applications. It consists of:

MongoDB (Database)
Express.js (Backend framework)
React.js (Frontend framework)
Node.js (Runtime environment)

MERN allows developers to use JavaScript for both the frontend and backend, making development easier and more efficient.

Why Choose MERN?

JavaScript Everywhere – Use JavaScript for the entire application (frontend, backend, and database queries).
Fast Development – React and Node.js offer rapid development and high performance.
Scalability – Suitable for small to large applications.
Open Source – All technologies in MERN are open source and have a strong community.

Setting Up a MERN Project

1. Install Node.js

Download and install Node.js from nodejs.org. It includes npm (Node Package Manager), which we’ll use to install dependencies.

2. Initialize a Project

Create a new folder for your project and initialize it:

mkdir my-mern-app

cd my-mern-app

npm init -y

3. Set Up the Backend (Node.js & Express.js)

Install Express.js:

npm install express mongoose dotenv cors

Create a Basic Server (server.js):
const express = require("express");  
const mongoose = require("mongoose");  
const cors = require("cors");  
require("dotenv").config();  

const app = express();  
app.use(express.json());  
app.use(cors());  

const PORT = process.env.PORT || 5000;  

app.get("/", (req, res) => {  
  res.send("MERN Stack Backend is Running!");  
});  

app.listen(PORT, () => console.log(`Server running on port ${PORT}`));

Connect to MongoDB

Create a MongoDB Atlas account and get your MongoDB URI.
Install Mongoose to interact with MongoDB.
Update your server.js to connect MongoDB

mongoose.connect(process.env.MONGO_URI, { useNewUrlParser: true, useUnifiedTopology: true, }) .then(() => console.log("MongoDB Connected")) .catch(err => console.log(err));

4. Set Up the Frontend (React.js)

Install React:

npx create-react-app client

cd client

npm start

Install Dependencies:

npm install axios react-router-dom

Create a Simple Component (App.js):

import React, { useEffect, useState } from "react";  
import axios from "axios";  

function App() {  
  const [message, setMessage] = useState("");  

  useEffect(() => {  
    axios.get("http://localhost:5000/")  
      .then(response => setMessage(response.data))  
      .catch(error => console.log(error));  
  }, []);  

  return (  
    <div>  
      <h1>MERN Stack App</h1>  
      <p>{message}</p>  
    </div>  
  );  
}  

export default App;