gistfile1.js

var Basket = function() {
  this.count = 5;
};

Basket.prototype.count = 1;

var x = new Basket();
console.log(x.count); // 1 or 5? (and why?)

// and
var Basket = function() {};
Basket.prototype.count = 1;

var x = new Basket();
x.count = 5;
console.log(x.count); // 1 or 5? (and why?)

First one prints 5 for prototypical reasons. It first tries to find count on the object and then on prototype. As it finds the key on the object itself, 5 is returned.

In second case, Basket.count doesn't set it on the object or prototype. Rather it makes count key on the function object itself. So x.count simply gets the count of prototype. Hence, 1.

@chinchang The second case would also log 5 for the same reason as the first case. x is the object returned by the constructor function, not a reference to the function so it would try to access x.count and find it before looking for x.__proto__.count

The two examples are essentially equivalent.

@mrappleton Ahh...my bad :) you are right.

Sorry for the confusion @chinchang @mrappleton - I made a mistake in my example facepalm. The second example was wrong - as you point out setting Basket.count doesn't really do much of value. Updated it now.

haha. I was wondering how come I wrote the second O/P wrong :P