TypeScript Tutorial 2026: Why You Must Switch from JS

Image: AI-Generated Custom

By Abhijeet • Jan 2, 2026 • 6 Min Read

JavaScript is chaos. TypeScript is order. In 2026, writing plain JavaScript is considered a liability for large projects. TS catches errors before you run code. Here is why and how.

The Problem with JavaScript

// JavaScript
function add(a, b) {
  return a + b;
}
add("10", 20); // Returns "1020" -> BUG!

The TypeScript Solution

// TypeScript
function add(a: number, b: number): number {
  return a + b;
}
add("10", 20); // Error: Argument of type 'string' is not assignable to 'number'.

The editor tells you immediately. No runtime crashes.

Core Concepts

1. Types

string, number, boolean
any (avoid this!)
void (returns nothing)

2. Interfaces

Define the shape of an object.

interface User {
  id: number;
  name: string;
  isAdmin?: boolean; // Optional
}

Why It Matters for AI

When working with massive JSON responses from LLMs (GPT-4), you need to know exactly what the data looks like. TypeScript ensures your code handles the data structure correctly every time.

Final Verdict

🎯 Start Today

Change your file from .js to .ts. Fix the red squiggly lines. Congratulations, you are now a better developer.