Comments on: Uniform Event Model: Making IE think W3C

By: Tavs Dokkedahl

Tavs Dokkedahl — Thu, 26 Jul 2007 19:52:25 +0000

@ Steve Brewer. I found a way to support innerHTML – it might contain beta errors but the approach seems good. Try it out if you like.

@ Kevin Hoang Le. You can only have two event handlers of the same type with the same function registered for any one element – hence it can execute twice at maximum. The loopNum variable is only in the code for testing purposes. It tells how many times to test the loop. It is not an integral part of UEM and thus does not count in the result for the code perfomance.

By: Stephan Baumeister

Stephan Baumeister — Wed, 25 Jul 2007 10:03:03 +0000

@ibolmo
“100 * O(n)” is not a correct statement, as you can’t multiply a number with a collection of functions (thats what the big O notation represents).
In computer sience “100*n = O(n)” is quite right. It has the same meaning as f(n)=100*n is element of O(n).
See: http://en.wikipedia.org/wiki/Big_O_notation

By: Kevin Hoang Le

Kevin Hoang Le — Tue, 24 Jul 2007 19:36:59 +0000

Tavs, I don’t understand why you said the inner loop executes only twice at a maximum (in your response to Jason). But IF that’s the case, then since the outer loop is 100 times always, the growth rate would then be independent of the size of the inputs. The the big-oh should be O(1). (Constant factor is dropped in big-oh notation).

By: Tavs Dokkedahl

Tavs Dokkedahl — Tue, 24 Jul 2007 16:48:36 +0000

Thanks for the comments.

@ Steve Brewer. I am working on replacing the existing innerHTML method. Note however that this method is not in the W3C recommendations. But since it is wildly supported and used (and misused) it would be a good idea to support it.

@ Jason. The perfomance tests are not scientifically correct. They are my best shoot at an upper bound on the worst case scenario. You’re right that 2 for loops would produce O(n^2) but the inner loop is executed only twise at a maximum. Therefore I feel it is closer to the real world to regard the inner loop as a constant – hence the O(n) result.

@ Braden Anderson. If you look at the code you will see that there is no resemblence with UEM and the original code of Scott Andrew. UEM does not use the native addEvent nor removeEvent() methods. It currently uses the fireEvent method to enulate dispatchEvent although it is not strictly nessesary. The addEvent() method you are refering to is a nice solution but falls short in many places.

By: Braden Anderson

Braden Anderson — Tue, 24 Jul 2007 15:31:46 +0000

I haven't looked at the code, but I suspect it has the same problems with this mentioned in PPK's addEvent() considered harmful.

By: ibolmo

ibolmo — Tue, 24 Jul 2007 14:38:14 +0000

Yes 100 * n != O(n) but, 100 * O(n) :P.

By: Stephan Baumeister

Stephan Baumeister — Tue, 24 Jul 2007 13:59:48 +0000

The outer loop runs a constant number (100) of times: 100*n = O(n) !

By: Jason

Jason — Tue, 24 Jul 2007 13:41:54 +0000

Maybe I’m rusty on my algorithm time complexity theory, but on the perf page in the creator’s documentation he lists two algorithms that include nested loops as O(n). That sounds more like O(n^2) or at best maybe O(n log n) to me. Feel free to correct me if I’m wrong, computational theorists.

By: Fabian Jakobs

Fabian Jakobs — Tue, 24 Jul 2007 13:08:36 +0000

Sometimes it seems that the time is right for some ideas. We are currently working on moving qooxdoo’s DOM event handling code to it’s own layer, independent of the widget stuff. This event layer will have some of the same features, e.g. support for the capturing phase in IE and unified event objects modeled after the W3C DOM standard. Special mouse and key event handlers are responsible for normalizing event sequences and in the case of the key handler computing the key identifier. Another interesting feature, which we have brought from the IE to the other browsers is mouse event capturing.

Early documentation can ba found here: http://qooxdoo.org/documentation/general/dom_event_layer

By: Steve Brewer

Steve Brewer — Tue, 24 Jul 2007 11:41:21 +0000

Interesting. What happens if you alter the DOM using innerHTML? Will the resulting nodes by “UEMed”?