Prev: FAQ Topic - Why does simple decimal arithmetic give strange results? (2008-04-22)
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From: pr on 22 Apr 2008 12:21
Piotr K wrote:
> Here's the GetStyle code:
>
> function GetStyle(obj, style) {
> obj = document.getElementById(obj);
>
> if(style == "opacity") return GetOpacity(obj);
>
> if(obj.currentStyle) return obj.currentStyle[style];
> else if(window.getComputedStyle) return getComputedStyle(obj,
> "").getPropertyValue(style.replace(/[A-Z]/g, function(obj, ch) {return
> "-"+style.charAt(ch).toLowerCase()}));
> }
>
> However I don't think this has anything to do with that strange
> behaviour. In the example I posted earlier it returns simply "Red", so
> in other words
>
> GetStyle("box", "backgroundColor") == "Red"

Not quite. It appears in fact to return '"red"' - that is, a string
containing double quote marks, which is not a sensible input for
style.backgroundColor. Try this, for example:

alert("*" + GetStyle("box", "backgroundColor") + "*");

Opera doesn't do it after the value has been set in code to
'transparent', so you may have to do a bit of research to find out when
it occurs. My guess is when you use a named colour.

A troublesome one to spot.
From: Piotr K on 22 Apr 2008 12:44
On 22 Kwi, 18:21, pr <p...(a)porl.globalnet.co.uk> wrote:
> Piotr K wrote:
> > Here's the GetStyle code:
>
> > function GetStyle(obj, style) {
> > obj = document.getElementById(obj);
>
> > if(style == "opacity") return GetOpacity(obj);
>
> > if(obj.currentStyle) return obj.currentStyle[style];
> > else if(window.getComputedStyle) return getComputedStyle(obj,
> > "").getPropertyValue(style.replace(/[A-Z]/g, function(obj, ch) {return
> > "-"+style.charAt(ch).toLowerCase()}));
> > }
>
> > However I don't think this has anything to do with that strange
> > behaviour. In the example I posted earlier it returns simply "Red", so
> > in other words
>
> > GetStyle("box", "backgroundColor") == "Red"
>
> Not quite. It appears in fact to return '"red"' - that is, a string
> containing double quote marks, which is not a sensible input for
> style.backgroundColor. Try this, for example:
>
> alert("*" + GetStyle("box", "backgroundColor") + "*");
>
> Opera doesn't do it after the value has been set in code to
> 'transparent', so you may have to do a bit of research to find out when
> it occurs. My guess is when you use a named colour.
>
> A troublesome one to spot.

You're absolutely right, all because of double quote marks returned by
GetStyle, I can't believe I missed that, thank you sooo much - now
everything works fine :)

Thanks for all responses!
From: Thomas 'PointedEars' Lahn on 22 Apr 2008 14:52
VK wrote:
> On Apr 22, 3:52 am, Piotr K <piotr.korzeniew...(a)gmail.com> wrote:
>> document.getElementById("box").style.backgroundColor = "transparent";
>
> "transparent" is an imaginary value. It was used in W3C docs to describe
> an element that has no color property set, like "transparent element",
> but it was not meant to be an actual string to assign to the style.

Wrong on all accounts, see

http://www.w3.org/TR/CSS2/colors.html#background-properties
http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-58190037
http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSStyleDeclaration
http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSS2Properties

> Now it is supported by some newer browsers due to misreading some badly
> written W3C samples. Neither Opera not IE6 are one of them.

Or maybe, just *maybe*, you are simply completely wrong *again* because both
user agents do support that string value. I guess it does not bother you to
be corrected all the time because a simple test -- like

var elemRef = document.body.getElementsByTagName("*")[0];
if (elemRef && typeof elemRef.style != "undefined")
{
elemRef.style.backgroundColor = "red";
window.alert("Now it should have a red background.");
elemRef.style.backgroundColor = "transparent";
window.alert("Now it should have a transparent background.");
}

-- before making further wild assumptions would have sufficed.

Nevertheless, your stating nonsense has been helpful this time as I could
find out that the `style' property and the shorthand CSS properties (for
example elemRef.style.backgroundColor) are in fact supported by W3C DOM
Level 2 CSS and _not_ a (fully) proprietary feature as I thought before.


PointedEars
--
var bugRiddenCrashPronePieceOfJunk = (
navigator.userAgent.indexOf('MSIE 5') != -1
&& navigator.userAgent.indexOf('Mac') != -1
) // Plone, register_function.js:16
From: VK on 22 Apr 2008 16:21
On Apr 22, 10:52 pm, Thomas 'PointedEars' Lahn <PointedE...(a)web.de>
wrote:
> Wrong on all accounts, see
>
> http://www.w3.org/TR/CSS2/colors.html#background-properties
> http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-58190037
> http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSStyleDeclaration
> http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSS2Properties

Some day I will maybe understand how anything written on W3C may force
to work it on browser X. Some day...

> I guess it does not bother you to
> be corrected all the time because a simple test -- like
>
> var elemRef = document.body.getElementsByTagName("*")[0];
> if (elemRef && typeof elemRef.style != "undefined")
> {
> elemRef.style.backgroundColor = "red";
> window.alert("Now it should have a red background.");
> elemRef.style.backgroundColor = "transparent";
> window.alert("Now it should have a transparent background.");
> }

So it works now, even on IE6? Great. I still highly suggest never use
direct assignments for rule reset: use "" instead. Nobody is obligated
to follow this advise of course.

> Nevertheless, your stating nonsense has been helpful this time as I could
> find out that the `style' property and the shorthand CSS properties (for
> example elemRef.style.backgroundColor) are in fact supported by W3C DOM
> Level 2 CSS and _not_ a (fully) proprietary feature as I thought before.

Since DOM 1 to be exact. But better later than never :-)
From: Thomas 'PointedEars' Lahn on 22 Apr 2008 16:57
VK wrote:
> [...] Thomas 'PointedEars' Lahn [...] wrote:
>> Wrong on all accounts, see
>>
>> http://www.w3.org/TR/CSS2/colors.html#background-properties
>> http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-58190037
>> http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSStyleDeclaration
>> http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSS2Properties
>
> Some day I will maybe understand how anything written on W3C may force
> to work it on browser X. Some day...

It is *implemented as specified*, Often Wrong.

>> I guess it does not bother you to
>> be corrected all the time because a simple test -- like
>>
>> var elemRef = document.body.getElementsByTagName("*")[0];
>> if (elemRef && typeof elemRef.style != "undefined")
>> {
>> elemRef.style.backgroundColor = "red";
>> window.alert("Now it should have a red background.");
>> elemRef.style.backgroundColor = "transparent";
>> window.alert("Now it should have a transparent background.");
>> }
>
> So it works now, even on IE6?

Now? Even? It works with *all* IE versions that support the `style'
property, so since version 4.0 (documented and tested). Your attempts to
conceal your cluelessness are even more ridiculous than your clueless
boasting itself is.

> Great. I still highly suggest never use direct assignments for rule reset:
> use "" instead. Nobody is obligated to follow this advise of course.

I would hope so, because your advice does not present an equivalent solution
at all. Assigning the empty string resets the style property to its initial
value (which ISTM to be a proprietary feature, CMIIW), but the cascade may
cause the computed value of the property to be a completely different one.

>> Nevertheless, your stating nonsense has been helpful this time as I could
>> find out that the `style' property and the shorthand CSS properties (for
>> example elemRef.style.backgroundColor) are in fact supported by W3C DOM
>> Level 2 CSS and _not_ a (fully) proprietary feature as I thought before.
>
> Since DOM 1 to be exact. But better later than never :-)

Wrong again. W3C DOM Level 1 only reserved the `style' attribute of the
HTMLElement interface for future use, and it did not include a section on
CSS interfaces. Furthermore, W3C DOM Level 1 HTML is rendered (and marked)
obsolete by DOM Level 2 HTML since quite a while.

http://www.w3.org/TR/REC-DOM-Level-1/level-one-html.html#ID-011100101
http://www.w3.org/TR/DOM-Level-2-HTML/ ("Status of this document", "Note:")

Someone like you who continuously fails to get the basic facts right should
be *very* slow to boast. Probably someone has told you that before.


PointedEars
--
Use any version of Microsoft Frontpage to create your site.
(This won't prevent people from viewing your source, but no one
will want to steal it.)
-- from <http://www.vortex-webdesign.com/help/hidesource.htm>
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