Welcome to JavaScript classes! A class in JavaScript is a blueprint for creating objects with shared properties and methods. Classes were introduced in ES6 as syntactic sugar over JavaScript's existing prototype-based inheritance. They encapsulate data and behavior, making object-oriented programming more intuitive. The class acts as a template that can create multiple object instances, each with their own data but sharing the same structure and methods.
Let's examine the syntax for defining a JavaScript class. We use the class keyword followed by the class name. The constructor method is special - it runs automatically when we create a new instance. Inside the constructor, we use the this keyword to set properties on the instance being created. Regular methods are defined directly in the class body. To create an instance, we use the new keyword followed by the class name and any required arguments.
Now let's see how to create and use objects from our class. We create instances using the new keyword followed by the class name and constructor arguments. Each object gets its own copy of the properties but shares the methods. We can access properties and call methods using dot notation. Notice how person1 and person2 are separate objects with their own data - Alice is 30 years old while Bob is 25, and each returns different values when we call their methods.
JavaScript classes offer advanced features for more sophisticated programming. You can use extends for inheritance, allowing one class to inherit properties and methods from another. Private fields, marked with a hash symbol, can only be accessed within the class. Static methods belong to the class itself, not instances. Getters and setters provide controlled access to properties. The super keyword calls parent class methods. This example shows a Student class extending Person with a private student ID field and overridden greet method.
To summarize what we've learned about JavaScript classes: Classes serve as blueprints for creating objects with consistent structure and behavior. The constructor method initializes each instance with its own data. Methods are shared across all instances, promoting code reuse. Advanced features like inheritance and private fields enable sophisticated object-oriented design. Classes make JavaScript code more organized, readable, and maintainable.