Node.js TypeScript

TypeScript is a programming language built on top of JavaScript that adds:

• Static typing

• Interfaces

• Classes

• Compile-time error checking

• Better tooling & IntelliSense

Node.js works extremely well with TypeScript, especially for large backend projects.

✅ 1. Install TypeScript

Globally:

Locally in a project:

✅ 2. Initialize TypeScript in a Node.js Project

This generates:

This file controls TypeScript behavior (ES target, module system, root folders, strict mode, etc.)

✅ 3. Important tsconfig.json Settings (Node.js)

Recommended settings:

Meaning:

• target: ES version output

• module: Node uses CommonJS

• outDir: compiled .js files

• rootDir: where .ts source files stay

• strict: enable full type checking

• esModuleInterop: allows import express from "express"

✅ 4. Create Your First TypeScript File

Create a folder and file:

Example:

✅ 5. Compile TypeScript to JavaScript

This generates:

✅ 6. Run the Compiled JavaScript With Node

🚀 7. Auto-compile & Auto-run (ts-node + nodemon)

Install useful packages:

Run TypeScript directly without compiling:

For auto-reload, add this in package.json:

Run development mode:

✔️ 8. Using TypeScript with Node.js Modules

Importing built-in modules:

Exporting functions:

Importing:

✔️ 9. Typing Objects & Functions

✔️ 10. Interfaces

✔️ 11. Classes in TypeScript

✔️ 12. Using Express with TypeScript

Install types:

Example app.ts:

⭐ Summary Table