23 Inheritance

The ES6 class syntax also supports inheritance using the extends keyword

• When one class inherits the attributes and methods of another class that is called inheritance.
• The class whose properties and methods are inherited is known as the Parent class.
• The class that inherits the properties from the parent class is the Child class.
• To create a class inheritance, use extends keyword.
• Always use super() in the child class constructor

1. Real World Example

• Car is a super set, and Ford, Mercedes etc are children of the parent class. They use the basic features of Car in general and then have their brand specific features.
• Son inherits all the properties and mannerisms from a father. Father and Son can stay in the same address, son can inherit the assets however the age will not be same.

class Father{
    
    constructor(){
        console.log("Father is called..");
        this.address = "10 Park Street";
        this.assets = "$125000";
    }

    getaddress(){
        console.log(`Address is ${this.address}`);
    }

    getassets(){
        console.log(`Asset worth is ${this.assets}`);
    }

}

class Son extends Father{
     constructor(age){
         super();
         console.log("Son is called..");
         this.age = age;
     }

     getage(){
        console.log(`My age is ${this.age}`);
     }
}

const ranveer = new Son(21);
ranveer.getaddress();
ranveer.getassets();
ranveer.getage();

2. Another Example

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

  makeSound() {
    console.log(`${this.name} says ${this.sound}`);
  }
}

class Dog extends Animal {
  constructor(name) {
    super(name, 'Woof');
  }
}

const dog = new Dog('Rex');
dog.makeSound(); // Output: "Rex says Woof"