On 12/16/06, David <[EMAIL PROTECTED]> wrote:
I asked that question a few days ago, so i will pass the knowledge :)
>
> 1, $('#id')
calls the javascript function getElementById so that is the fastest.
> 2, $('tag#id')
is slow because jquery gets all the tags first and then searches for the
id
A possible way to speed up $("tag#id") is to do $("#id").is("tag")
That will first run getElementById, and then test if it matches the
selector.
You would probably see dramatic speed gains by converting something like:
$(".class > .otherClass tr#id td#id") into $("#id").id(".class > .otherClass
tr#id td")
since a search by ID at any point is really just a search by ID which also
tests whether that node matches the early selectors/filters.
> 3, $('.class',context)
the performance depends on the context
Well sort of. $(".class", context) where context is $("#id")[0] is the same
thing as $("#id .class")
4, $('#id .class')
> 5, $('.class1 .class2')
4 is faster than 5 because of the getElementById function
Indeed. 4 is way faster than 5. Anytime you can narrow something down by ID,
do it. getElementById is blazingly fast, and will help all around.
This is was i understood from the answers. Correct me if i made a
mistake somewhere.
David
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Yehuda Katz
Web Developer | Wycats Designs
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