🗂️ Chapter 5 — Structuring a TypeScript Project

Now that you know how to use TypeScript, it’s time to organize your code like a real developer.
A good structure helps you:

• stay focused,
• avoid messy folders,
• and work in teams more easily.

Let’s build a clean mini-project structure.

---

🏗️ Folder structure (basic version)

my-app/
├── main.ts
├── utils/
│   └── math.ts
├── types/
│   └── index.ts
├── README.md

You’ll use:

• main.ts: your entry point
• utils/: for reusable logic
• types/: for interfaces and types
• README.md: to describe your project

Let’s build it step by step.

---

📁 Step 1 — Create the project folder

mkdir my-app
cd my-app
code .

---

📄 Step 2 — Create a simple main.ts

// main.ts
import { add } from "./utils/math.ts";

console.log(add(2, 3));

---

🔧 Step 3 — Create a utils/math.ts file

// utils/math.ts
export function add(a: number, b: number): number {
  return a + b;
}

🧠 export makes the function available in other files.

---

🧱 Step 4 — Add some types

Create types/index.ts:

// types/index.ts
export interface User {
  name: string;
  age: number;
  isAdmin?: boolean; // optional
}

Then use it in main.ts:

import type { User } from "./types/index.ts";

const bob: User = {
  name: "Bob",
  age: 42,
};

console.log(bob);

🧠 import type is optional, but helps with clarity.

---

💡 Naming conventions (recap)

File / Folder	Purpose
main.ts	Entry point of the app
utils/	Reusable functions
types/	All your interfaces/types
README.md	Project description

📘 Learn more: TypeScript Modules

---

🧪 Try it out

If you used tsx:

tsx main.ts

With Deno:

deno run --allow-read main.ts

✅ You should see the result of the addition and the user object.

---

📦 Going further

In larger projects, you will see:

• lib/ — for technical tools
• api/ — for business logic
• config/, tests/, bin/ — for configuration, testing, or scripts

These folders help split your code by function, not just by type.

📘 Check out:

• Official Project References Guide
• Node.js Module Resolution

---

✅ What’s next?

In the next chapter, we’ll learn how to use Git and GitHub to save your work, collaborate with others, and share your code online.

👉 Go to Chapter 6: Introduction to Git and GitHub