interface

Defines the shape of an object type. Interfaces are open (can be extended with declaration merging) and are erased at runtime.

Syntax

typescript

interface Name {
  property: type;
  optionalProp?: type;
  method(param: type): returnType;
}

Example

typescript

interface User {
  id: string;
  name: string;
  email: string;
  role?: "admin" | "user";
}

function greet(user: User): string {
  return `Hello, ${user.name}`;
}