Rails spinoffs - Jun 2007 - Element.hasClassName() performance issue ?

Hi,

I made a performance test:

  Element.hasClassName(ahref.parentNode,''myclass'')

It seems this medthod is really time consuming compared to:

  ahref.parentNode.classNames && ahref.parentNode.classNames

- Is it true ?
- Should hasClassName() be used in loop or not ?

I''m using prototype 1.5.1rc3 but it seems nothing change in 1.5.1 on
the code  I talked about.

Regards
-- 
Jean-Philippe Encausse - R&D Jalios SA
Jp [at] encausse.net - http://www.encausse.com - http://www.jalias.com
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Hey,

Jean-Philippe Encausse a écrit :
> It seems this medthod is really time consuming compared to:
It shouldn''t.  It''s actually as fast as it should get.  The
code you
posted as comparison was obviously truncated, what''s the full version?

I suspect the real cost in it is element extension, and you''re on IE...
  On an already-extended element, it should be very fast.

Maybe there is an alternate way of achieving the overall processing 
you''re going for (the loop, or whatever)?

-- 
Christophe Porteneuve aka TDD
tdd-x+CfDp/qHev2eFz/2MeuCQ@public.gmane.org

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Well, we saw by inspecting a simple code loop doing:

$A(this.elm.getElementsByTagName(''A'')).each(function(ahref,idx){

   if (!Element.hasClassName(ahref.parentNode,''disabled'')){
       return;
    }
}

That hasClassName() in a "slowed" IE take the most part of the time.
Well I know this loop is ugly we should use ?

this.elm.down(''A.disabled'');

But it is an example. So my question is: should we use Element.hasClassName()
in a loop
or something more straight ?


On 6/12/07, Christophe Porteneuve
<tdd-x+CfDp/qHev2eFz/2MeuCQ@public.gmane.org>
wrote:
>
>
> Hey,
>
> Jean-Philippe Encausse a écrit :
> > It seems this medthod is really time consuming compared to:
>
> It shouldn''t.  It''s actually as fast as it should get. 
The code you
> posted as comparison was obviously truncated, what''s the full
version?
>
> I suspect the real cost in it is element extension, and you''re on
IE...
>   On an already-extended element, it should be very fast.
>
> Maybe there is an alternate way of achieving the overall processing
> you''re going for (the loop, or whatever)?
>
> --
> Christophe Porteneuve aka TDD
> tdd-x+CfDp/qHev2eFz/2MeuCQ@public.gmane.org
>
> >
>

-- 
Jean-Philippe Encausse - R&D Jalios SA
Jp [at] encausse.net - http://www.encausse.com - http://www.jalias.com
GTalk: jp.encausse [at] gmail.com - SMS: sms [at] jp.encausse.net
Mob: +33682125699 - Job: +33139239283 - Tel: +33139189015 - Fax:
+33958789015
Do it Once, Use it Twice ~ Do it Twice, Make It Once

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Hey,

Jean-Philippe Encausse a écrit :
> But it is an example. So my question is: should we use 
> Element.hasClassName() in a loop
> or something more straight ?
The more concise code is usually better :-)  After all, the $$ call will 
extend all elements it returns, too.  Note, btw, that your call:

	$$(''a.disabled'')

is NOT equivalent to your manual loop: it doesn''t look for disabled 
classes in the parent nodes of links, but on the links themselves. 
You''d want:

	$$(''.disabled > a'')

However, if using hasClassName is critical for whatever reason to your 
code, you should not be too fearful: hasClassName, 
getElementsByClassName, Element.ClassNames are currently supposed to get 
some TLD in Prototype 1.6.

-- 
Christophe Porteneuve aka TDD
tdd-x+CfDp/qHev2eFz/2MeuCQ@public.gmane.org

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