24. What are classes in ES6?

In ES6 (ECMAScript 2015), classes are a syntactical sugar over JavaScript's prototype-based inheritance. They provide a more structured and readable way to define objects and work with object-oriented programming (OOP) principles like encapsulation, inheritance, and polymorphism.

Defining a Class

You can define a class using the class keyword:

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

  // Method
  greet() {
    console.log(`Hello, my name is ${this.name} and I am ${this.age} years old.`);
  }
}

// Creating an instance of the class
const person1 = new Person("John", 25);
person1.greet(); // Output: Hello, my name is John and I am 25 years old.

Key Features of ES6 Classes

1. Constructor Method:
   • The constructor method is a special method that is called when a new object is created.
2. Methods in Classes:
   • Methods inside a class do not require the function keyword.
3. Inheritance (Extending Classes):
   • Classes support inheritance using the extends keyword.

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class Student extends Person {
  constructor(name, age, grade) {
    super(name, age); // Calls the parent class constructor
    this.grade = grade;
  }

  study() {
    console.log(`${this.name} is studying in grade ${this.grade}.`);
  }
}

const student1 = new Student("Alice", 20, "10th");
student1.greet(); // Inherited method
student1.study(); // Output: Alice is studying in grade 10th.

4. Getters and Setters:
   • You can define getters and setters to control access to class properties.

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class Car {
  constructor(brand) {
    this._brand = brand;
  }

  get brand() {
    return this._brand;
  }

  set brand(newBrand) {
    this._brand = newBrand;
  }
}

const myCar = new Car("Toyota");
console.log(myCar.brand); // Toyota
myCar.brand = "Honda";
console.log(myCar.brand); // Honda

5. Static Methods:
   • Static methods belong to the class itself and not to instances.

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class MathUtils {
  static add(a, b) {
    return a + b;
  }
}

console.log(MathUtils.add(5, 3)); // 8

Conclusion

ES6 classes provide a more structured and intuitive way to work with objects and inheritance in JavaScript. They help in writing cleaner, modular, and maintainable code while still using JavaScript’s prototype-based nature under the hood. 🚀