What Is TypeScript and Why Should You Use It?

JavaScript is the language of the web — but it has some weaknesses. Debugging large projects gets harder, refactoring becomes risky, and teamwork grows more complex. TypeScript was born to solve these problems.

What Is TypeScript?

TypeScript is a programming language developed by Microsoft that's a superset of JavaScript. It adds a type system to JavaScript and catches errors at compile time.

Every valid JavaScript code is valid TypeScript — but TypeScript offers extra power.

JavaScript vs TypeScript

// JavaScript — Runtime error
function add(a, b) {
  return a + b;
}
add("5", 3); // "53" — unexpected result!

// TypeScript — Catches error at compile time
function add(a: number, b: number): number {
  return a + b;
}
add("5", 3); // ERROR! string can't be assigned to number

Why Should You Use TypeScript?

1. Early Error Catching

• Type errors caught at compile time
• Reduces runtime errors by 15-25%
• Refactoring becomes safe

2. Better Developer Experience

• Auto-completion (IntelliSense)
• Function parameters and return types visible
• Code is easier to read
• Navigation (go to definition)

3. Safety in Large Projects

• Reduced error risk in 10,000+ line projects
• Team members understand code more easily
• API contracts defined as types
• Refactoring updates all usages

4. Ecosystem Support

• React, Vue, Angular — all support TypeScript
• Next.js comes with TypeScript by default
• Used in Node.js backends too
• Most npm packages have type definitions

Core TypeScript Concepts

Basic Types

let name: string = "Cagri";
let age: number = 28;
let active: boolean = true;
let hobbies: string[] = ["coding", "music"];

Interface

interface User {
  id: number;
  name: string;
  email: string;
  age?: number; // optional
}

Type

type Status = "active" | "inactive" | "pending";
type ApiResponse<T> = {
  data: T;
  error: string | null;
};

Generics

function firstElement<T>(array: T[]): T | undefined {
  return array[0];
}

TypeScript Usage Statistics

| Metric | Value | |--------|-------| | npm downloads (weekly) | 50M+ | | GitHub stars | 97K+ | | Companies using it | Microsoft, Google, Airbnb, Slack | | Stack Overflow popularity | Top 5 most loved language | | New projects | 78% choose TypeScript |

When Should You Use TypeScript?

Use it:

• Medium-large scale projects
• Team projects (2+ developers)
• Long-lived projects
• API development
• Library/framework development

May not need it:

• Small scripts
• Quick prototypes
• One-off tools
• Very simple web pages

Getting Started with TypeScript

Installation:

npm install -g typescript
tsc --init

With Next.js:

npx create-next-app@latest --typescript

Learning Resources:

• TypeScript Handbook — Official documentation
• TypeScript Playground — Try in browser
• Total TypeScript — Matt Pocock's course
• Type Challenges — Practice exercises

Conclusion

TypeScript has become the standard tool for modern web development. If you know JavaScript, learning TypeScript is easy and the payoff is enormous. Fewer bugs, better developer experience, and more sustainable code — developing with TypeScript is a level up.

If you'd like to build modern web applications with TypeScript or learn it, get in touch: info@cagribilgehan.com. Check out my projects: cagribilgehan.com