In TypeScript interfaces, ?: denotes optional properties. Here's an example:

interface User {
    name: string;
    age?: number; // Optional
}

const user1: User = { name: "Joe Mama" }; // Age is optional
const user2: User = { name: "Tony", age: 30 };

console.log(user1); // Output: { name: "Joe Mama" }
console.log(user2); // Output: { name: "Tony", age: 30 }

#javascript #typescript