Why typed classes matter in Typescript - See It in Action

Why typed classes matter

📖 Scenario: Imagine you are building a simple app to manage books in a library. You want to keep track of each book's title and number of pages. Using typed classes helps you avoid mistakes and makes your code easier to understand.

🎯 Goal: You will create a typed class called Book with properties for title and pages. Then you will create an instance of this class and print its details.

📋 What You'll Learn

Create a class called Book with typed properties title: string and pages: number

Add a constructor to Book that sets title and pages

Create an instance of Book called myBook with title 'The TypeScript Guide' and pages 250

Print the book's title and pages using console.log

💡 Why This Matters

🌍 Real World

Typed classes are used in apps to keep data organized and safe, like managing books, users, or products.

💼 Career

Understanding typed classes is important for writing reliable TypeScript code in many software development jobs.

1

Create the typed class

Create a class called Book with typed properties title: string and pages: number. Add a constructor that takes title: string and pages: number and sets them to the class properties.

Typescript

# Your code here
// Create class Book with typed properties and constructor

Need a hint?

Use class keyword, declare properties with types, and write a constructor method.

2

Create an instance of the class

Create an instance of Book called myBook with title 'The TypeScript Guide' and pages 250.

Typescript

class Book {
  title: string;
  pages: number;

  constructor(title: string, pages: number) {
    this.title = title;
    this.pages = pages;
  }
}

// Create instance myBook here
# Your code here

Need a hint?

Use new Book('The TypeScript Guide', 250) and assign it to myBook.

3

Access and print properties

Use console.log to print the book's title and pages from the myBook instance. Print the title first, then the pages.

Typescript

class Book {
  title: string;
  pages: number;

  constructor(title: string, pages: number) {
    this.title = title;
    this.pages = pages;
  }
}

const myBook = new Book('The TypeScript Guide', 250);

// Print title and pages
# Your code here

Need a hint?

Use console.log(myBook.title) and console.log(myBook.pages).

4

Final output

Run the program to print the book's title and pages exactly as shown: first line The TypeScript Guide, second line 250.

Typescript

class Book {
  title: string;
  pages: number;

  constructor(title: string, pages: number) {
    this.title = title;
    this.pages = pages;
  }
}

const myBook = new Book('The TypeScript Guide', 250);

console.log(myBook.title);
console.log(myBook.pages);

// Run the program to see output

Need a hint?

Make sure you run the program and see the two lines printed exactly.