44 Prototype Inheritance

The prototypical inheritance defines how objects inherit properties and methods from other objects.

• In JavaScript, almost everything is an object
• objects can inherit properties and behaviors from other objects through their prototypes.

1. Without Inheritance

Let's say we have phone functions.

• Here we will notice getModelNumber is repeated

function Nokia() {
  this.modelNumber = "";
  this.getModelNumber = function () {
    return this.modelNumber;
  };
}

function Samsung() {
  this.modelNumber = "XX-XX-XXX";
  this.getModelNumber = function () {
    return this.modelNumber;
  };
  this.latestFeature = function () {
    console.log("Quad Camera");
  };
}


const samsungGalaxy = new Samsung();
console.log(samsungGalaxy.getModelNumber());

2. With Inheritance

• The samsung proto type object has inherited the phone properties/methods Samsung.prototype = new Phone()
• When we create any instance of the Samsung function we can access the inherited methods.

function Phone() {
  this.modelNumber = "";
  this.getModelNumber = function () {
    return this.modelNumber;
  };
}

function Samsung() {
  this.modelNumber = "XX-XX-XXX";
  this.latestFeature = function () {
    console.log("Quad Camera");
  };
}

Samsung.prototype = new Phone();

const samsungGalaxy = new Samsung();
console.log(samsungGalaxy.getModelNumber());

• While executing samsungGalaxy.getModelNumber() javascript checks if the methos is available in the function
• If it doesn't find, it goes one level up to the proto type of the Samsung function
• And it keeps going until it finds the method or null (the proto type of Ovject)