Question

Lets suppose I made a class called Person.

var Person = function(fname){this.fname = fname;};

pObj is the object I made from this class.

var pObj = new Person('top');

now I add one property to Person class, say lname.

Person.prototype.lname = "Thomsom";

now pObj.lname gets me “Thomson”.

My question is that, when pObj didn’t find the property lname in it, how does it know where to look for.

Answer 1

Every object has a prototype. When a properti is not set for object instance, it is looked in object’s prototype. In Gecko and WebKit, you can use object’s __proto__ property to get (or set) reference to its prototype.

You can get object prototype using standard myObj.constructor.prototype