What are classes in the context of object-oriented programming?

A class in OOP (object-oriented programming) is a template or blueprint for creating objects.

It defines:

• State (properties or fields): Data stored in objects of this class.
• Behavior (methods): Functions or actions that objects of this class can perform.

A class allows creating multiple objects of the same type with the same structure of properties and set of methods, but with unique property values. Instantiating a class creates an object that is an instance of this class.

Example:

// Definition of the Car class
class Car {
  // Constructor - method called when creating a new object
  constructor(brand, model, year) {
    this.brand = brand; // Property
    this.model = model; // Property
    this.year = year;   // Property
  }

  // Method
  startEngine() {
    console.log(`${this.brand} ${this.model} engine started.`);
  }
}

// Creating objects (instances) of the Car class
const myCar = new Car("Toyota", "Camry", 2022);
const partnerCar = new Car("Honda", "Civic", 2023);

// Using object methods
myCar.startEngine();
partnerCar.startEngine();

// Accessing object properties
console.log(myCar.brand);
console.log(partnerCar.year);