Advanced TypeScript Tricks

Mastering TypeScript means making the most of its type system. Here are three advanced tips you can use daily.

Conditional Types

type IsString<T> = T extends string ? true : false;
type A = IsString<'abc'>; // true
type B = IsString<123>;   // false

This type adapts depending on the input!

Utility Types

Use built-in utility types:

type User = { id: number; name: string; };
type PartialUser = Partial<User>; // All properties become optional

Mapped Types

Create new types based on existing ones:

type User = { id: number; name: string; };
type AllStrings = { [K in keyof User]: string };
// { id: string; name: string; }

Conclusion

Playing with these tools helps you write more robust and maintainable TypeScript code.