**Course Title:** Modern JavaScript Programming: From Fundamentals to Full-Stack Development **Section Title:** JavaScript Classes and OOP **Topic:** Introduction to Object-Oriented Programming (OOP) in JavaScript **What is Object-Oriented Programming (OOP)?** Object-Oriented Programming (OOP) is a programming paradigm that revolves around the concept of objects and their interactions. It's a way to design and organize code that simulates real-world objects and systems. OOP focuses on four main principles: 1. **Encapsulation**: Bundling data and methods into a single unit, making it easier to manage complexity. 2. **Abstraction**: Hiding unnecessary details and exposing only the necessary information to the outside world. 3. **Inheritance**: Creating a new class based on an existing one, inheriting its properties and behavior. 4. **Polymorphism**: Ability of an object to take on multiple forms, depending on the context. **Why OOP in JavaScript?** JavaScript supports OOP concepts, making it a versatile language for building complex applications. With the introduction of ES6 classes, JavaScript has become even more OOP-friendly. Here's why you should learn OOP in JavaScript: 1. **Better code organization**: OOP helps you structure your code into reusable, modular components. 2. **Easier maintenance**: OOP promotes encapsulation, making it easier to modify and update your code. 3. **Improved collaboration**: OOP concepts like inheritance and polymorphism facilitate teamwork and code reuse. **Key OOP Concepts in JavaScript** 1. **Classes**: Templates for creating objects, defining properties and methods. 2. **Objects**: Instances of classes, having their own set of properties and methods. 3. **Constructors**: Special methods that initialize objects when created. 4. **Methods**: Functions that belong to objects or classes, performing specific tasks. 5. **Inheritance**: Creating a new class based on an existing one, inheriting its properties and behavior. **Practical Example:** Suppose we want to model a simple bank account system using OOP in JavaScript. We can create a `BankAccount` class with properties like `accountNumber` and `balance`, and methods like `deposit` and `withdraw`. ```javascript class BankAccount { constructor(accountNumber, initialBalance) { this.accountNumber = accountNumber; this.balance = initialBalance; } deposit(amount) { this.balance += amount; } withdraw(amount) { if (amount > this.balance) { console.log("Insufficient funds"); } else { this.balance -= amount; } } } const account = new BankAccount("1234567890", 1000); console.log(account.balance); // Output: 1000 account.deposit(500); console.log(account.balance); // Output: 1500 account.withdraw(200); console.log(account.balance); // Output: 1300 ``` **What's Next?** In the next topic, we'll dive deeper into defining classes, constructors, and methods in JavaScript. You'll learn how to create complex classes, inherit behavior from parent classes, and use methods to perform specific tasks. **External Resources:** * MDN Web Docs: [JavaScript Classes](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes) * W3Schools: [JavaScript OOP](https://www.w3schools.com/js/js_oop.asp) **Leave a Comment/Ask for Help:** If you have any questions, need help with the topic, or want to share your experience, please leave a comment below. Do you have any questions about this topic before proceeding?