TypeScript generics unlock powerful type-safe abstractions. This guide demystifies generics and explores advanced type system features.
Why Generics?
Generics enable writing reusable code that works with multiple types while maintaining type safety. They eliminate code duplication and prevent runtime errors.
function identity<T>(arg: T): T {
return arg;
}
const num = identity<number>(42);
const str = identity<string>("hello");Generic Constraints
Constraints limit generic types to specific shapes, enabling access to properties and methods while maintaining flexibility.
interface HasLength {
length: number;
}
function logLength<T extends HasLength>(arg: T): void {
console.log(arg.length);
}Utility Types
TypeScript provides built-in utility types like Partial, Pick, Omit, and Record. These transform existing types to create new ones.
type User = {
id: string;
name: string;
email: string;
};
type PartialUser = Partial<User>;
type UserPreview = Pick<User, "id" | "name">;Advanced Patterns
Conditional types, mapped types, and template literal types enable sophisticated type transformations and inference.
Conclusion
Mastering TypeScript generics and advanced types elevates code quality and developer experience. Start simple and gradually incorporate advanced patterns.
Key Takeaways
Generics provide type-safe code reuse
Use constraints to access properties safely
Utility types eliminate boilerplate
Type inference reduces explicit annotations
Advanced types enable powerful abstractions