Introduction to TypeScript: Why Types Matter

TypeScript adds static typing to JavaScript, catching errors at compile time rather than runtime. This leads to more maintainable, self-documenting code. If you've ever spent hours debugging 'undefined is not a function', TypeScript is your new best friend.

Why TypeScript?

• Catch bugs before they reach production
• Better IDE support with autocomplete and refactoring
• Self-documenting code that's easier to understand
• Gradual adoption - add types incrementally to existing projects

Your First Type

// Define an interface for your data shape
interface User {
  name: string;
  age: number;
  email?: string;  // Optional property
}

// Now TypeScript knows exactly what a User looks like
const user: User = {
  name: "Alice",
  age: 30
};

// This would be a compile error:
// user.age = "thirty"; // Type 'string' is not assignable to type 'number'

// TypeScript also helps with functions
function greet(user: User): string {
  return `Hello, ${user.name}!`;
}

Type Inference

You don't always need to explicitly declare types. TypeScript is smart enough to infer types from context. This keeps your code clean while maintaining type safety.

// TypeScript infers these types automatically
const message = "Hello";  // string
const count = 42;         // number
const items = [1, 2, 3];  // number[]

// Function return types are also inferred
function add(a: number, b: number) {
  return a + b;  // TypeScript knows this returns number
}