Adding method to a class using prototype : Member Function « Object Oriented « JavaScript Tutorial

<HTML>
<HEAD>
<TITLE>Instance method demo</TITLE>
</HEAD>
   <BODY>
   <H1>
   <SCRIPT>
   // constructor function
   function Rectangle(height, width){
      this.height =  height;
      this.width = width;
   }
  
   function getArea () {
      return this.height * this.width;
   }
   // turn the function into an object method
   Rectangle.prototype.calcArea = getArea;

   var theRectangle = new Rectangle (3, 5);
   theRectangle.width = 10;

   document.write("The rectangle instance height is: " + theRectangle.height + "<br>");
   document.write("The rectangle instance width is: " + theRectangle.width  + "<br>");
   document.write ("The calcArea method returns: " + theRectangle.calcArea());
   </SCRIPT>
   </H1>
   </BODY>
</HTML>

25.4.Member Function
	25.4.1.	Defining the object methods outside of the factory functions and then pointing to them
	25.4.2.	Create an Object with member method
	25.4.3.	Add member function
	25.4.4.	Adding method to a class using prototype
	25.4.5.	Custom objects and associative object arrays
	25.4.6.	Instance method
	25.4.7.	Call object member function