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Message-ID: <1395223.HDI7Dnh15d@PointedEars.de>
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To: Thomas 'PointedEars' Lahn <cljs@PointedEars.de>
Organization: PointedEars Software (PES)
Date: Sat, 11 Feb 2012 15:21:52 +0100
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Subject: Re: getComputedStyle vs currentStyle with IE 9
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Thomas 'PointedEars' Lahn wrote:

> Andrew Poulos wrote:
>> I think you are misleading me as it doesn't look like there's a better
>> way.
> 
> Wrong on both accounts.  For crying out loud, a *closely related* question
> has been asked (presumably, *again*) on StackOverflow *yesterday*, and I
> have commented on the other answers there, eventually referring to
> JSX:css.js (which does not consider getPropertyValue() yet – as the
> shorthand is optional, and potentially less efficient thanks to
> camel-casing –, but soon):
> […] 
>> but that doesn't really resolve the fact getComputedStyle will fail with
>> IE 9 and camel-cased CSS properties.
> 
> Wrong (just tested again).  getComputedStyle() "fails" with IE
> 9(.0.8112.16421 on Windows 7) in *Compatibility* Mode, but not in
> Standards Mode, and it "fails" in IE < 9, of course.

Well, *partially* wrong.  getComputedStyle() does not fail with IE 9 per se.  
But it does fail even in Standards Mode with camel-cased CSS properties 
because getPropertyValue() expects the *real* CSS property name.  It is 
specified so in the W3C DOM Level 2 Style Specification:

<http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSStyleDeclaration>

You MUST *only* camel-case the property name (e. g., "marginTop" instead of 
"margin-top") when you are accessing style object properties:

<http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSS2Properties>

Hence my assumption that the use of getPropertyValue() might turn out to be 
more efficient than using the optional shorthand with the camel-cased 
property name, especially as you need to map "float" to "cssFloat" or 
"styleFloat" aso.


PointedEars
-- 
> If you get a bunch of authors […] that state the same "best practices"
> in any programming language, then you can bet who is wrong or right...
Not with javascript. Nonsense propagates like wildfire in this field.
  -- Richard Cornford, comp.lang.javascript, 2011-11-14