Introduction to TypeScript: Why Types Matter
Learn why TypeScript has become essential for modern JavaScript development and how to get started with type-safe code.
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
}Start with strict mode enabled (strict: true in tsconfig.json). It's easier to start strict than to add strictness later.
About Sarah Chen
Senior tech writer with 10+ years of experience covering AI, cloud computing, and developer tools. Previously at TechCrunch and Wired.