Class

In object-oriented programming (OOP), a class is a blueprint for creating objects (instances) that share similar properties and behaviors. A class defines the structure and behavior of objects, including their properties (attributes) and methods (functions).

Classes are a fundamental concept in OOP and are used to create objects that encapsulate data and functionality. Each object created from a class is known as an instance of that class and inherits its properties and methods. Classes provide a way to model real-world entities and define their behavior in a structured and reusable manner.

Key Concepts of Classes:

1. Properties (Attributes): Properties are the data members of a class that define the characteristics or state of an object. They represent the object’s attributes.
2. Methods (Functions): Methods are the functions defined within a class that define the behavior or actions that an object can perform.
3. Constructor: A constructor is a special method in a class that is used to initialize new objects. It is called automatically when a new object is created.
4. Inheritance: Inheritance is a mechanism in OOP that allows a class to inherit properties and methods from another class. It promotes code reusability and helps in creating a hierarchy of classes.
5. Encapsulation: Encapsulation is the concept of bundling the data (properties) and methods that operate on the data (methods) into a single unit (class). It helps in data hiding and abstraction.
6. Polymorphism: Polymorphism is the ability of objects to take on multiple forms. It allows objects of different classes to be treated as objects of a common superclass.

Example:

class Animal {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }

  speak() {
    console.log(`${this.name} is speaking.`);
  }
}

// Creating an instance of the Animal class
const dog = new Animal('Buddy', 5);
dog.speak(); // Output: Buddy is speaking.

In this example, Animal is a class that defines the blueprint for creating animal objects. The constructor method is used to initialize the name and age properties of an animal object, and the speak method defines the behavior of an animal speaking.