TypeScript18 min readTypeScript Interfaces Deep
Go deeper into interfaces: optional props, readonly, extension, and implementing interfaces in classes.
Interfaces describe object shapes. ## Basic ```ts interface User { id: number; name: string; } ``` ## Optional & readonly ```ts interface User { readonly id: number; name: string; email?: string; } ``` ## Extend interface ```ts interface Admin extends User { role: "admin"; } ``` ## Implement in class ```ts class Person implements User { constructor(public id: number, public name: string) {} } ``` ## Graph ```mermaid flowchart TD A[User] --> B[Admin extends] ``` ## Remember - Interfaces define contracts - Great for APIs and models