[jQuery] Re: what does this selector mean ?
On Oct 18, 2009, at 2:05 AM, Michael Geary wrote:
$('div',this) is simply a confusing way of writing $
(this).find('div'). The only reason it exists at all is for
"historical reasons": it was added to jQuery before the .find()
method existed.
Never use $('div',this) in your code. Always use $(this).find('div')
instead. It is easier to read and faster too.
-Mike
Right on!
--Karl
[jQuery] Re: what does this selector mean ?
Yes, in fact the snippet you posted shows why $(context).find(selector) is
faster. $(selector,context) *calls* $(context).find(selector). By calling
$(context).find(selector) directly, you avoid this extra call and the checks
that lead to it. Therefore, $(context).find(selector) is faster by a very
small constant amount.
The improved readability is the more important point. $(selector,context) is
backwards from the normal parent-child order in CSS selectors, and it isn't
self-documenting the way $(context).find(selector) is.
There's no reason for $(selector,context) to exist at all, except for
backwards compatibility with jQuery code written in 2006. It should be
deprecated.
-Mike
On Sun, Oct 18, 2009 at 1:53 AM, MorningZ wrote:
>
> Faster? aren't they just equivalent?
>
> according to the comments in the library file they are
>
> // HANDLE: $(expr, [context])
> // (which is just equivalent to: $(content).find(expr)
>} else
> return jQuery( context ).find( selector );
>
> On Oct 18, 2:05 am, Michael Geary wrote:
> > $('div',this) is simply a confusing way of writing $(this).find('div').
> The
> > only reason it exists at all is for "historical reasons": it was added to
> > jQuery before the .find() method existed.
> >
> > Never use $('div',this) in your code. Always use $(this).find('div')
> > instead. It is easier to read and faster too.
> >
> > -Mike
> >
> > On Tue, Sep 29, 2009 at 4:24 AM, runrunforest
> wrote:
> >
> > > Hi,
> >
> > > $('div', this) what does that mean ?
>
[jQuery] Re: what does this selector mean ?
Faster? aren't they just equivalent?
according to the comments in the library file they are
// HANDLE: $(expr, [context])
// (which is just equivalent to: $(content).find(expr)
} else
return jQuery( context ).find( selector );
On Oct 18, 2:05 am, Michael Geary wrote:
> $('div',this) is simply a confusing way of writing $(this).find('div'). The
> only reason it exists at all is for "historical reasons": it was added to
> jQuery before the .find() method existed.
>
> Never use $('div',this) in your code. Always use $(this).find('div')
> instead. It is easier to read and faster too.
>
> -Mike
>
> On Tue, Sep 29, 2009 at 4:24 AM, runrunforest wrote:
>
> > Hi,
>
> > $('div', this) what does that mean ?
[jQuery] Re: what does this selector mean ?
$('div',this) is simply a confusing way of writing $(this).find('div'). The
only reason it exists at all is for "historical reasons": it was added to
jQuery before the .find() method existed.
Never use $('div',this) in your code. Always use $(this).find('div')
instead. It is easier to read and faster too.
-Mike
On Tue, Sep 29, 2009 at 4:24 AM, runrunforest wrote:
>
> Hi,
>
> $('div', this) what does that mean ?
>
[jQuery] Re: what does this selector mean ?
It's a little confusing, but the difference is that the "contextual
selector" is a second argument, whereas the "or selector" is a comma
within a single argument. So, if we forget about "this" for a moment:
$('.myclass, #myid')
-- matches all elements that have a class of "myclass" or id="myid"
-- both selectors are contained within the same argument (i.e. the
same set of quotation marks)
$('.myclass', '#myid')
-- matches all elements that have a class of "myclass" and are
descendants of an element with id="myid"
-- two arguments.
One way to include "this" in the selection would be to use .add(). For
example:
$(this).add('div');
-- select this and all div elements.
Hope that helps.
--Karl
Karl Swedberg
www.englishrules.com
www.learningjquery.com
On Oct 17, 2009, at 10:40 PM, lampy wrote:
I know Karl's answer is correct, but from the docs (
http://docs.jquery.com/Selectors/multiple#selector1selector2selectorN
) I would've thought the comma meant "select all div elements, and
this".
Is there any documentation that would help me understand this?
On Sep 29, 10:03 pm, MorningZ wrote:
oops... that'll teach me to try to make sense first thing in the
morning :-)
Coffee first THEN post
On Sep 29, 9:11 pm, Karl Swedberg wrote:
On Sep 29, 2009, at 7:33 AM, MorningZ wrote:
Whatever "this" is in that case, it's the context to look for any
(jQuery will only select 's that are ancestors of
"this" in
the DOM tree)
Correction: for $('div',this), jQuery will only select s that
are descendants of "this" in the DOM tree.
--Karl
Karl Swedbergwww.englishrules.comwww.learningjquery.com
[jQuery] Re: what does this selector mean ?
I know Karl's answer is correct, but from the docs (
http://docs.jquery.com/Selectors/multiple#selector1selector2selectorN
) I would've thought the comma meant "select all div elements, and
this".
Is there any documentation that would help me understand this?
On Sep 29, 10:03 pm, MorningZ wrote:
> oops... that'll teach me to try to make sense first thing in the
> morning :-)
>
> Coffee first THEN post
>
> On Sep 29, 9:11 pm, Karl Swedberg wrote:
>
> > On Sep 29, 2009, at 7:33 AM, MorningZ wrote:
>
> > > Whatever "this" is in that case, it's the context to look for any
> > > (jQuery will only select 's that are ancestors of "this" in
> > > the DOM tree)
>
> > Correction: for $('div',this), jQuery will only select s that
> > are descendants of "this" in the DOM tree.
>
> > --Karl
>
> >
> > Karl Swedbergwww.englishrules.comwww.learningjquery.com
[jQuery] Re: what does this selector mean ?
oops... that'll teach me to try to make sense first thing in the
morning :-)
Coffee first THEN post
On Sep 29, 9:11 pm, Karl Swedberg wrote:
> On Sep 29, 2009, at 7:33 AM, MorningZ wrote:
>
>
>
> > Whatever "this" is in that case, it's the context to look for any
> > (jQuery will only select 's that are ancestors of "this" in
> > the DOM tree)
>
> Correction: for $('div', this), jQuery will only select s that
> are descendants of "this" in the DOM tree.
>
> --Karl
>
>
> Karl Swedbergwww.englishrules.comwww.learningjquery.com
[jQuery] Re: what does this selector mean ?
On Sep 29, 2009, at 7:33 AM, MorningZ wrote:
Whatever "this" is in that case, it's the context to look for any
(jQuery will only select 's that are ancestors of "this" in
the DOM tree)
Correction: for $('div', this), jQuery will only select s that
are descendants of "this" in the DOM tree.
--Karl
Karl Swedberg
www.englishrules.com
www.learningjquery.com
[jQuery] Re: what does this selector mean ?
Whatever "this" is in that case, it's the context to look for any (jQuery will only select 's that are ancestors of "this" in the DOM tree)
