RegExp to test for pixel values might be unreliable in IE 9

[thomas.jaggi@…]

IE 9 (tested in version 9.0.8112 on Windows 7) does not seem to return rounded decimal pixel values when using currentStyle. Therefore, the regular expression used to detect pixel values (/^{-?\d+(?:px)?$/i) is not working properly there: ​http://jsfiddle.net/YPDHF/1/}

[dmethvin]

Confirmed.

[tomgrohl]

Tested a fix. Added an example here: ​http://jsfiddle.net/tomgrohl/Accr3/

Contains the fix:

newrnumpx = /^-?\d+(?:\.\d+)?(?:px)?$/i

Which works in IE9 for both 3px and 3.14px.

@dmethvin if your happy with this I can create a pull request.

[thomas.jaggi@…]

@tomgrohl: Thanks for the additional tests! However, If I remember it correctly, the corresponding code block was only relevant for IE.

[tomgrohl]

@thomas.jaggi@…: Yes true. I'll amended comment

The fix is still relevant for IE though, which is good.

[dmethvin]

@tomgrohl, if you could create a pull request that would be great! Can we have a unit test case as well?

[tomgrohl]

Yes sure I'll get on it.

[tomgrohl]

Pull request ​here

Includes Unit Tests

[Rick Waldron]

Please see pull request comments.

[Timmy Willison]

Thanks for your work. Since not all browsers (including webkit and firefox) support decimal pixel values, I think we should simply suggest that users stick with integer values. It keeps the code simpler and smaller.

[tomgrohl]

@timmywil

I agree, as I was I only looking into fixing it for IE only Iassumed it would work in other browsers. How wrong I was, lol.

[thomas.jaggi@…]

I disagree. First of all, the respective code block is relevant for IE only anyway, as far as I remember. And I'd say this is not about 'sticking with integer values' since it happens when computing the size of something set in relative units l(ike em or %) which does not correspond to an integer px value.

[thomas.jaggi@…]

Well, to be fair, I should probably test that first, but I'm on my iPhone right know... But I think I stumbled upon this when trying to get the font size of an element set in em.

[tomgrohl]

It has been found that it is an issue in other browsers, not just IE.

The problem is that the behaviour is not consistent, and would not be possible to fix.

[dmethvin]

Oh man this test was totally off base and I should have caught it.

First, there is no jQuery in the test case, it's got code snipped from places *inside* jQuery but nothing showing that jQuery is doing anything wrong in a real-life case.

Second, IE9 supports getComputedStyle so it doesn't even go through the currentStyle section of code -- another hazard of code clipping rather than a real test case.

Third, several browsers including Firefox and IE9 return fractional pixels from getComputedStyle and we appear to round properly to the nearest pixel when returning those values:

​http://jsfiddle.net/tY8Cd/3/

So this ticket seems more like invalid or worksforme, there's nothing yet shown that needs fixing.

[thomas.jaggi@…]

Argh, sorry for wasting your time, I obviously didn't think that through.

[addyosmani]

Confirmed with timmywil we can remove the needsdocs on this one.