Inheritance through Prototyping

The second and more robust method to establish a class hierarchy is by creating an object of the superclass and then assign it as a prototype of the subclass object. Suppose our superclass is superClass and our subclass is subClass. The prototype assignment would look like this:

subClass.prototype = new superClass;

 this.inheritFrom = superClass;
  this.inheritFrom();

Here is the new code:

function superClass() {

  this.bye = superBye;
  this.hello = superHello;
}

function subClass() {
  this.bye = subBye;
}
subClass.prototype = new superClass;

function superHello() {
  return "Hello from superClass";
}
  
function superBye() {
  return "Bye from superClass";
}

function subBye() {
  return "Bye from subClass";
}

Click here to invoke the following script that creates an instance of subClass():

function printSub() {
  var newClass = new subClass();
  alert(newClass.bye());
  alert(newClass.hello());
}

Next: How to add properties after the object is created