Create a Node.js App with TypeScript, Express, Mongoose and MongoDB Atlas

In this post, we will go through on how to build a modern Node.js application using TypeScript, Express.js, and MongoDB Atlas, following a modular folder structure. We’ll also integrate dotenv for managing environment variables and use ts-node-dev for a smooth development workflow.

✅ Step 1: Initialize Your Project

Create a new directory and initialize a Node.js project:

mkdir my-node-app && cd my-node-app
npm init -y

✅ Step 2: Set Up TypeScript

Install TypeScript and initialize the configuration:

npm install --save-dev typescript
npx tsc --init

Now, open the generated tsconfig.json and update the following properties:

{
"rootDir": "./src",
"outDir": "./dist",
"strict": true,
"moduleResolution": "node",
"esModuleInterop": true,
"target": "es6",
"module": "commonjs"
}

✅ Step 3: Project Structure

Create a modular folder structure:

mkdir src
touch src/server.ts

We’ll build everything inside the src/ directory.

✅ Step 4: Install Core Dependencies

Install essential packages:

npm install mongodb express mongoose cors dotenv

Install type definitions for TypeScript:

npm install --save-dev @types/express @types/cors

✅ Step 5: Enable Hot Reloading

Install ts-node-dev to auto-reload the app when files change:

npm install --save-dev ts-node-dev

Update your package.json scripts:

"scripts": {
"dev": "ts-node-dev --respawn --transpile-only src/server.ts"
}

✅ Step 6: Add Environment Configuration

Create a .env file in the root directory:

PORT=3000
MONGODB_URI=mongodb+srv://<db_username>:<db_password>@primary-cluster.t9drt.mongodb.net/<db_name>?retryWrites=true&w=majority&appName=Primary-Cluster

Then, create a config folder:

mkdir src/config
touch src/config/index.ts

Inside src/config/index.ts:

import dotenv from 'dotenv';
dotenv.config();
export const PORT = process.env.PORT || 5000;
export const MONGODB_URI = process.env.MONGODB_URI as string;

✅ Step 7: Set Up the Server

Edit src/server.ts:

import express from 'express';
import mongoose from 'mongoose';
import cors from 'cors';
import { PORT, MONGODB_URI } from './config';
const app = express();
// Middlewares
app.use(cors());
app.use(express.json());
// Sample route
app.get('/', (_req, res) => {
res.send('API is running...');
});
// Connect to MongoDB and start server
mongoose
.connect(MONGODB_URI)
.then(() => {
console.log('Connected to MongoDB Atlas');
app.listen(PORT, () => {
console.log(`Server is running on http://localhost:${PORT}`);
});
})
.catch((error) => {
console.error('MongoDB connection error:', error);
});

✅ Step 8: Run Your App

Use the script to start your development server:

npm run dev

If everything is set up properly, you’ll see:

Connected to MongoDB Atlas
Server is running on http://localhost:3000

This is a clean, modular Node.js app powered by TypeScript, Express, and MongoDB Atlas. This foundation is perfect for building scalable APIs with environment separation and type safety.

Category: Knowledge,Learning