How to set up TypeScript with Node.js and Express (2023)

In this article, we’ll cover a Best way to set up TypeScript in an Express app, understanding the basic constraints that come with it.

Table of contents

Create a package.json file
Installing TypeScript & other dependencies
Generating tsconfig.json
Create an Express server with a .ts extension
Watching file changes and build directory

1. Create initial folder and package.json

mkdir node-express-typescript
cd node-express-typescript
npm init --yes

After initialize a package.json file , The newly created file might look something like the following code:

{
  "name": "Your File Name",
  "version": "1.0.0",
  "description": "",
  "main": "index.js", // Entry Point change it from  js to .ts 
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "type": "module",
  "keywords": [],
  "author": "",
  "license": "ISC"
}

2. Installing TypeScript & other dependencies

npm install express mongoose cors mongodb dotenv

npm install  -D typescript ts-node-dev @types/express @types/cors

3. Generating tsconfig.json

npx tsc --init

The command above will generate a new file called tsconfig.json with the following default compiler options:

target: es2016
module: commonjs
strict: true
esModuleInterop: true
skipLibCheck: true
forceConsistentCasingInFileNames: true

After opening the tsconfig.json file, you’ll see a lot of other compiler options that are commented out. In tsconfig.json, compilerOptions is a mandatory field that needs to be specified

Set the rootDir and outDir as src and dist folder

{
  "compilerOptions": {
    "outDir": "./dist"

    // other options remain same
  }
}

4. Create an Express server with a .ts extension

Create a file name index.ts open it


import express, { Express, Request, Response , Application } from 'express';
import dotenv from 'dotenv';

//For env File 
dotenv.config();

const app: Application = express();
const port = process.env.PORT || 8000;

app.get('/', (req: Request, res: Response) => {
  res.send('Welcome to Express & TypeScript Server');
});

app.listen(port, () => {
  console.log(`Server is Fire at http://localhost:${port}`);
});

5. Watching file changes and build directory

npm install  nodemon

After installing these dev dependencies, update the scripts in the package.json file:

{

  "scripts": {
    "build": "npx tsc",
    "start": "node dist/index.js",
    "dev": "nodemon index.ts"
  }
}

6. Run The Code

npm run dev

if everything if perfect you will see the message in console of
Server is Fire at http://localhost:8000

Sukanta Das @cristain