Circle Radius | Code Sharing Demonstration

 var Circle = {
   area: function(r) {
     return r * Math.PI;
   },
   toString: function(r, unit) { // buitin func toString()
     unit = (unit === "international" ? "mm" : "inch"); // Ternary
     return "Radius = " + this.area(r) + " " + unit;
   }
 };

 var newCircle = Circle.toString(10, "international");

 document.addEventListener('DOMContentLoaded', function() {
   var element = document.getElementById("result");
   element.innerHTML = newCircle.toString();
 });