Comments on: Techy Treasures #3: When is a mouseout not a mouseout?

By: brothercake

brothercake — Thu, 27 Nov 2008 22:25:36 +0000

Yeah we totally could do that, but:

- prototyping to built-ins is not a good idea generally, for the reasons discussed

- I personally prefer to work with consistent code-base – to have every browser do the same thing, rather than one use a custom method and one use its own – if that’s possible; it just makes me feel more confident

By: boen_robot

boen_robot — Thu, 27 Nov 2008 13:40:02 +0000

I’m confused… IE7 and below don’t support prototyping (IE8 does btw), and other browsers do… yet, IE has the method we want to define, right?

So… can’t we just do
if (!Object.prototype.contains) { //Define the contains() method as part of the prototype }

And then use the contains() method as in IE. IE will use their built-in method (even in IE8, since the contains() method still exists), and everyone else will be using our method.

By: ashwin

ashwin — Wed, 26 Nov 2008 15:39:41 +0000

Can you provide a simple example?

By: Dan

Dan — Tue, 25 Nov 2008 12:20:01 +0000

Your contains method is so simple I did a double take before I got it :)

But we shouldn’t prototype custom methods to built-in objects, especially in code that other people will be working with, because those methods will show up in enumerators, potentially causing major problems for scripting that isn’t expecting them.

I also stay away from doing this in my code, but when using libraries working with other existing code I have got into the habit of using hasOwnProperty when iterating.

Anyway, nice article.