What are advanced TypeScript interfaces and how can I use them?

What are advanced TypeScript interfaces and how can I use them?

Advanced TypeScript interfaces allow you to define complex types, including optional properties, readonly properties, and index signatures. They help in creating more robust and maintainable code.

Can you give me an example of an interface with optional properties?

Sure! Here's an example:

interface User {
  id: number;
  name: string;
  email?: string; // optional property
}

In this example, the email property is optional.

What about using interfaces with classes?

You can implement interfaces in classes to enforce a contract. For example:

class Person implements User {
  id: number;
  name: string;
  email?: string;

  constructor(id: number, name: string, email?: string) {
    this.id = id;
    this.name = name;
    this.email = email;
  }
}

How do I use index signatures in interfaces?

Index signatures allow you to define properties dynamically. For example:

interface StringArray {
  [index: number]: string;
}
const myArray: StringArray = ['Hello', 'World'];