**Course Title:** Mastering TypeScript: From Basics to Advanced Applications **Section Title:** Working with Types and Interfaces **Topic:** Implement a TypeScript program that uses interfaces and various types.(Lab topic) In this lab, we will put our understanding of interfaces and various types into practice by implementing a TypeScript program. We will create an example of a simple bookstore application, where we'll define interfaces for authors and books, and create sample data to demonstrate the usage of these interfaces. ### Step 1: Define Interfaces for Authors and Books First, let's create interfaces for authors and books: ```typescript // author.interface.ts export interface Author { id: number; name: string; email: string; } // book.interface.ts export interface Book { id: number; title: string; author: Author; publicationYear: number; genres: string[]; } ``` In the `author.interface.ts` file, we define the `Author` interface with properties `id`, `name`, and `email`. In the `book.interface.ts` file, we define the `Book` interface with properties `id`, `title`, `author`, `publicationYear`, and `genres`. Note that the `author` property is of type `Author`, demonstrating interface composition. ### Step 2: Create Sample Data Next, let's create sample data for authors and books: ```typescript // data.ts import { Author } from './author.interface'; import { Book } from './book.interface'; const authors: Author[] = [ { id: 1, name: 'John Doe', email: 'john.doe@example.com' }, { id: 2, name: 'Jane Doe', email: 'jane.doe@example.com' }, ]; const books: Book[] = [ { id: 1, title: 'Book 1', author: authors[0], publicationYear: 2020, genres: ['Fiction'] }, { id: 2, title: 'Book 2', author: authors[1], publicationYear: 2022, genres: ['Non-Fiction'] }, ]; ``` In the `data.ts` file, we import the `Author` and `Book` interfaces and create sample data for authors and books. ### Step 3: Use Interfaces in a TypeScript Program Finally, let's use the interfaces and sample data in a TypeScript program: ```typescript // main.ts import { authors } from './data'; import { books } from './data'; function printAuthor(author: Author) { console.log(`Author: ${author.name} (${author.email})`); } function printBook(book: Book) { console.log(`Book: ${book.title} by ${book.author.name} (Published in ${book.publicationYear})`); console.log(`Genres: ${book.genres.join(', ')}`); } authors.forEach((author) => printAuthor(author)); books.forEach((book) => printBook(book)); ``` In the `main.ts` file, we import the sample data and define two functions: `printAuthor` and `printBook`. We then use these functions to print the author and book information to the console. ### Key Takeaways * Interfaces can be used to define the shape of objects and ensure type safety. * Interfaces can be composed to create more complex interfaces. * Using interfaces can help improve code readability and maintainability. ### What to Do Next * Practice defining and using interfaces in your own TypeScript projects. * Experiment with different types of interfaces, such as interfaces with optional properties or interfaces with methods. * Review the official TypeScript documentation on interfaces for more information. [https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#interfaces](https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#interfaces) Leave a comment or ask for help if you have any questions or need further clarification on this topic. In the next topic, we will cover understanding classes, constructors, and inheritance in TypeScript.