JavaScript Polymorphism

The polymorphism is a core concept of an object-oriented paradigm that provides a way to perform a single action in different forms. It provides an ability to call the same method on different JavaScript objects. As JavaScript is not a type-safe language, we can pass any type of data members with the methods.

JavaScript Polymorphism Example 1

Let’s see an example where a child class object invokes the parent class method.

<script>  

class A  

  {  

     display()  

    {  

      document.writeln("A is invoked");  

    }  

  }  

class B extends A  

  {  

  }  

var b=new B();  

b.display();  

</script>

Output:

A is invoked

Example 2

Let’s see an example where a child and parent class contains the same method. Here, the object of child class invokes both classes method.

<script>  

class A  

  {  

     display()  

    {  

      document.writeln("A is invoked<br>");  

    }  

  }  

class B extends A  

  {  

    display()  

    {  

      document.writeln("B is invoked");  

    }  

  }  

  

var a=[new A(), new B()]  

a.forEach(function(msg)  

{  

msg.display();  

});  

</script>

Output:

A is invoked
B is invoked

Example 3

Let’s see the same example with prototype-based approach.

<script>  

function A()  

{  

}  

A.prototype.display=function()  

{  

  return "A is invoked";  

}  

function B()  

{  

    

}  

  

B.prototype=Object.create(A.prototype);  

  

var a=[new A(), new B()]  

  

a.forEach(function(msg)  

{  

  document.writeln(msg.display()+"<br>");  

});  

<script>

Output:

A is invoked
B is invoked