Advanced TypeScript Types That Will Improve Your Code

TypeScript's type system is incredibly powerful and goes far beyond basic type annotations. In this article, we'll explore advanced TypeScript types that can help you write more robust and maintainable code.

1. Conditional Types

Conditional types allow you to create types that depend on other types.

`typescript
type ApiResponse = T extends string
? { message: T }
: { data: T };

type StringResponse = ApiResponse; // { message: string }
type DataResponse = ApiResponse; // { data: User }
`

2. Mapped Types

Mapped types let you create new types by transforming properties of existing types.

`typescript
type Partial = {
[P in keyof T]?: T[P];
};

type ReadOnly = {
readonly [P in keyof T]: T[P];
};
`

3. Template Literal Types

Template literal types enable you to create types from string templates.

`typescript
type EventName = on${Capitalize};

type ClickEvent = EventName<'click'>; // 'onClick'
type HoverEvent = EventName<'hover'>; // 'onHover'
`

4. Utility Types

TypeScript provides many built-in utility types that can save you time and make your code more expressive.

`typescript
interface User {
id: number;
name: string;
email: string;
}

type CreateUser = Omit;
type UserEmail = Pick;
type PartialUser = Partial;
`

Conclusion

These advanced TypeScript features can significantly improve your development experience and help you catch errors at compile time rather than runtime. Start incorporating them into your projects gradually, and you'll see immediate benefits in code quality and maintainability.