Sorry I´m in dependency on Analysis of Algorithm for second time LOL
ps: is true.
On 5/24/07, Rob Desbois <[EMAIL PROTECTED]> wrote:
No, because then people might think it was just because of jQuery that a
looped function call is slow.
The avoidance of repeated unnecessary function calling inside loops is
something that any programmer in any language should look at and immediately
say "Yuck!" :-D
--rob
On 5/24/07, Jean Nascimento <[EMAIL PROTECTED]> wrote:
>
> I´m a javascript nooba, so thanks for the tip :D
>
> On 5/23/07, Gordon <[EMAIL PROTECTED]> wrote:
> >
> > It is one of those blindingly obvious things but also easy to forget.
> > I suppose the tip should be "if you find $ in a loop, find a way to
> > cache it".
> >
> > On May 23, 4:43 pm, "Rob Desbois" <[EMAIL PROTECTED] > wrote:
> > > Absolutely, no loop should call a determinate function with the same
> > > argument(s) on every iteration.
> > > In other words, if a function is called in a loop and it will return
the
> > > same value for each iteration take it OUT of the loop.
> > >
> > > Also Gordon, remember that no more memory is used here - in the slow
version
> > > the result from .children() has to be cached somewhere in a temporary
> > > variable internally (I would guess, my knowledge of JS internals is
> > > minimal). Making the temporary variable explicit will use no
additional
> > > memory.
> > >
> > > --rob
> > >
> > > On 5/23/07, Gordon <[EMAIL PROTECTED]> wrote:
> > >
> > >
> > >
> > >
> > >
> > > > This one's probably blindingly obvious to anyone with any
significant
> > > > programming experience in javascript, but it's an easy one to forget
> > > > too.
> > >
> > > > Consider this code:
> > >
> > > > function fast ()
> > > > {
> > > > var myDivItems = $('#myDiv').children();
> > > > for (x = 0; x < 1000; x++)
> > > > {
> > > > myDivItems.length;
> > > > }
> > > > }
> > > > function slow ()
> > > > {
> > > > for (x = 0; x < 1000; x++)
> > > > {
> > > > $('#myDiv').children().length;
> > > > }
> > > > }
> > >
> > > > Both are functionally identical, but try profiling their run times
in
> > > > Firebug!
> > >
> > > > Here's the average run times I got from running each function 5
times
> > >
> > > > fast: 3.125ms
> > > > slow: 3146.875ms
> > >
> > > > One more line of code, a bit more memory used, but huge win in
loops.
> > >
> > > --
> > > Rob Desbois
> > > Eml: [EMAIL PROTECTED]
> > > Tel: 01452 760631
> > > Mob: 07946 705987
> > > "There's a whale there's a whale there's a whale fish" he cried, and
the
> > > whale was in full view.
> > > ...Then ooh welcome. Ahhh. Ooh mug welcome.
> >
> >
>
>
> --
>
> []´s Jean
> www.suissa.info
>
> Ethereal Agency
> www.etherealagency.com
>
--
Rob Desbois
Eml: [EMAIL PROTECTED]
Tel: 01452 760631
Mob: 07946 705987
"There's a whale there's a whale there's a whale fish" he cried, and the
whale was in full view.
...Then ooh welcome. Ahhh. Ooh mug welcome.
--
[]´s Jean
www.suissa.info
Ethereal Agency
www.etherealagency.com
