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From: Peter Michaux on 28 Dec 2009 23:18
On Dec 28, 6:36 pm, David Mark <dmark.cins...(a)gmail.com> wrote:
> On Dec 28, 1:01 pm, Peter Michaux <petermich...(a)gmail.com> wrote:
>
> > On Dec 28, 11:32 am, moha297 <moha...(a)gmail.com> wrote:
>
> > > I want to get the top and left values for a div on the screen.
>
> > physical screen or upper-left corner of the page (which may be out of
> > view if the page is scrolled.)?
>
> > As Richard Cornford has mentioned here many times, this problem is not
> > solved in general. If your div has parents that scroll, have table
> > elements, is a button, etc, then the calculation of the div's upper-
> > left corner relative to the upper-left corner of the page is complex.
>
> It's been done.

I've never seen such code and whoever claims "it does everything" is
probably not correct.

> It's just not an advisable cross-browser design to
> rely on such complex code

The implication of that statement is that the code likely doesn't do
everything and so code that does everything doesn't really exist.

> when simpler options are available.

Agreed.

Peter
From: Peter Michaux on 28 Dec 2009 23:26
On Dec 28, 3:37 pm, Thomas 'PointedEars' Lahn <PointedE...(a)web.de>
wrote:
> moha297 wrote:
> > I want to get the top and left values for a div on the screen.
>
> > I have been using the code to calculate the top and left values.
>
> > var total1 = 0;
> > var total2 = 0;
> > while(element){
> > total1+=element.offsetTop;
> > total2+=element.offsetLeft;
> > try{
> > element=element.offsetParent;
> > }catch(E){
>
> Should be `e' as it does not refer to a constructor.

If we are now off topic, some folks like to write globals in all
capitals. Since that looks like it might be an (implied) global then
captial 'E' may be appropriate.



> > break;
> > }
> > }
>
> > For the same DOM TREE this code is giving a performance reading of
> > 30msec in IE8 and 80 to 200msec in IE6.
>
> That is unsurprising since that try...catch statement does not do anything
> useful here as the assignment is not going to fail:

The assignment will not fail but getting a host object's property may.


> In most cases you do not need to determine the absolute position of an
> element in the first place.

That is absolutely ;-) correct. I think I've only needed absolute
position once in the past couple years.

Peter
From: David Mark on 28 Dec 2009 23:26
On Dec 28, 11:18 pm, Peter Michaux <petermich...(a)gmail.com> wrote:
> On Dec 28, 6:36 pm, David Mark <dmark.cins...(a)gmail.com> wrote:
>
> > On Dec 28, 1:01 pm, Peter Michaux <petermich...(a)gmail.com> wrote:
>
> > > On Dec 28, 11:32 am, moha297 <moha...(a)gmail.com> wrote:
>
> > > > I want to get the top and left values for a div on the screen.
>
> > > physical screen or upper-left corner of the page (which may be out of
> > > view if the page is scrolled.)?
>
> > > As Richard Cornford has mentioned here many times, this problem is not
> > > solved in general. If your div has parents that scroll, have table
> > > elements, is a button, etc, then the calculation of the div's upper-
> > > left corner relative to the upper-left corner of the page is complex.
>
> > It's been done.
>
> I've never seen such code and whoever claims "it does everything" is
> probably not correct.

I'm not saying the last one I wrote does it all, but it covers most
(if not all) of the issues mentioned.

>
> > It's just not an advisable cross-browser design to
> > rely on such complex code
>
> The implication of that statement is that the code likely doesn't do
> everything and so code that does everything doesn't really exist.

Not exactly. I mean that even if it does work 100%, the code is quite
complex with multiple forks (shouldn't a first choice for a design).
From: Peter Michaux on 28 Dec 2009 23:28
On Dec 28, 10:26 pm, Peter Michaux <petermich...(a)gmail.com> wrote:
> On Dec 28, 3:37 pm, Thomas 'PointedEars' Lahn <PointedE...(a)web.de>
> wrote:
>
> > moha297 wrote:
> > > I want to get the top and left values for a div on the screen.
>
> > > I have been using the code to calculate the top and left values.
>
> > > var total1 = 0;
> > > var total2 = 0;
> > > while(element){
> > > total1+=element.offsetTop;
> > > total2+=element.offsetLeft;
> > > try{
> > > element=element.offsetParent;
> > > }catch(E){
>
> > Should be `e' as it does not refer to a constructor.
>
> If we are now off topic, some folks like to write globals in all
> capitals. Since that looks like it might be an (implied) global then
> captial 'E' may be appropriate.

Nevermind. I really don't use try-catch enough.

Peter
From: Peter Michaux on 28 Dec 2009 23:30
On Dec 28, 10:26 pm, David Mark <dmark.cins...(a)gmail.com> wrote:
> On Dec 28, 11:18 pm, Peter Michaux <petermich...(a)gmail.com> wrote:
>
>
>
> > On Dec 28, 6:36 pm, David Mark <dmark.cins...(a)gmail.com> wrote:
>
> > > On Dec 28, 1:01 pm, Peter Michaux <petermich...(a)gmail.com> wrote:
>
> > > > On Dec 28, 11:32 am, moha297 <moha...(a)gmail.com> wrote:
>
> > > > > I want to get the top and left values for a div on the screen.
>
> > > > physical screen or upper-left corner of the page (which may be out of
> > > > view if the page is scrolled.)?
>
> > > > As Richard Cornford has mentioned here many times, this problem is not
> > > > solved in general. If your div has parents that scroll, have table
> > > > elements, is a button, etc, then the calculation of the div's upper-
> > > > left corner relative to the upper-left corner of the page is complex.
>
> > > It's been done.
>
> > I've never seen such code and whoever claims "it does everything" is
> > probably not correct.
>
> I'm not saying the last one I wrote does it all, but it covers most
> (if not all) of the issues mentioned.

The case that Richard Cornford refers to is the case where the code
truly does it all. Even the full "etc" I mentioned.

Peter
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