How do you define an OOP class in JavaScript?

Question

Based on my observation, the book that I am reading about JavaScript states that there\'s an OOP with JavaScript? It doesn\'t tell much about it, I mean it wasn\'t explained

Answer 1

The following snippet may help you getting started with JavaScript's class-less, instance-based objects:

function getArea() {  
   return (this.radius * this.radius * 3.14);  
}  

function getCircumference() {  
   var diameter = this.radius * 2;  
   var circumference = diameter * 3.14;  
   return circumference;  
}

function Circle(radius) {  
   this.radius = radius;  
   this.getArea = getArea;  
   this.getCircumference = getCircumference;  
}

var bigCircle = new Circle(100);  
var smallCircle = new Circle(2);

alert(bigCircle.getArea());            // displays 31400  
alert(bigCircle.getCircumference());   // displays 618  
alert(smallCircle.getArea());          // displays 12.56  
alert(smallCircle.getCircumference()); // displays 12.56

Example from: SitePoint - JavaScript Object-Oriented Programming