this.method = function(){} VS obj.prototype.method = function (){}

Question

As a c#/.net dev, I love to toy around with JavaScript in my spare time -- creating my own libraries/frameworks and such. Admittedly, they\'re not much (really nothing more

Answer 1

this.method = function(){};

Only works for that specific instance.

Obj.prototype.method = function(){};

Will work for every instance of Obj

Though in order to take advantage of prototype you should do

var o = new Obj(); // Note that functions intended to be used with "new" should be capitalized

o.method();

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Dice Example

I'll assume you intended to return this in your dice() function.

That example is not really common, because calling a function does not create a new object. In your dice case you would be assigning a method to this, which inside the function is window the global object, and then returning it.

The outcome would be the same object (window) in both d1 and d2, with a method roll which would be reassigned in the 2nd call.

To achieve what you want you should create the instances with new, like this:

var d1 = new Dice(6); // remember capitalization is important here
var d2 = new Dice(20); 

This will however create 2 roll functions, which is correct but wastes memory since the function can be shared by doing:

Dice.prototype.roll = function() { /* return random awesomeness */ };

Hope that clarifies things