Bug 73941 - Handling of !important in inline style sets is broken
: Handling of !important in inline style sets is broken
: WebKit
: 528+ (Nightly build)
: Unspecified Unspecified
: P2 Normal
Assigned To:
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Reported: 2011-12-06 11:49 PST by
Modified: 2011-12-07 23:34 PST (History)

Testcase (167 bytes, text/html)
2011-12-06 11:50 PST, Boris Zbarsky
no flags Details
proposed fix (19.16 KB, patch)
2011-12-07 11:43 PST, Alexey Proskuryakov
hyatt: review+
Review Patch | Details | Formatted Diff | Diff


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Description From 2011-12-06 11:49:31 PST
Consider the attached testcase, which does:

      document.getElementById("x").style.color = "red !important";

Per http://dev.w3.org/csswg/cssom/#the-cssstyledeclaration-interface the behavior should be:

  Similarly for the table below, setting the IDL attribute in the first column must invoke
  setProperty() with as first argument the CSS property given in the second column on the same row,
  as second argument the given value, and no third argument.

and the definition of setProperty says:

  If parsing the value returns null terminate this algorithm.
     Note: value can not include "!important".

WebKit gets the setProperty part right, but not the idl attribute set part.  Gecko and IE9 get the idl attribute part right.
------- Comment #1 From 2011-12-06 11:50:10 PST -------
Created an attachment (id=118083) [details]
------- Comment #2 From 2011-12-06 11:53:30 PST -------
Not only that, but if I put a space after the '!' suddenly the color ends up green.  Which is just completely weird, since in CSS syntax a space is allowed after '!', so it's not like this is an accidental behavior due to using the normal CSS parser...
------- Comment #3 From 2011-12-07 10:44:38 PST -------
This behavior is a result of a fix in bug 8223. The claim there was that both IE and Firefox supported "!important" when setting property values via IDL attributes. What that always untrue, or did the behavior change since 2006?

> Not only that, but if I put a space after the '!' suddenly the color ends up green.

Yes, the fix for bug 8223 failed to take this into account.
------- Comment #4 From 2011-12-07 11:43:14 PST -------
Created an attachment (id=118242) [details]
proposed fix

I'm still puzzled why other browsers apparently turned around on this, but even in the absence of an explanation, if seems like we should do the same.
------- Comment #5 From 2011-12-07 11:46:19 PST -------
(From update of attachment 118242 [details])
------- Comment #6 From 2011-12-07 11:54:18 PST -------
Committed <http://trac.webkit.org/changeset/102262>.
------- Comment #7 From 2011-12-07 11:59:16 PST -------
Ah, interesting.

IE9 is weird.  On the testcase in this bug (even if I add a <body> to make their old parser happy), it ignores the style set in all modes.  On the testcase in bug 8223, it sets the style in quirks, IE7, and IE8 modes, but not in IE9 standards mode.  Do you see that too?

As for Gecko, it accepted all sorts of gunk in inline style until Gecko 1.9 as long as it started with a valid value followed by '!' or ';' (for example, style.color = "red; flowery petals" would have parsed, as would have "red! for it is so pretty").  This was fixed in https://bugzilla.mozilla.org/show_bug.cgi?id=383075

Thanks for the quick fix!
------- Comment #8 From 2011-12-07 13:36:15 PST -------
Thanks for the info. I didn't test IE very closely, just checked that your test passed.

We'll see if this change breaks any content.
------- Comment #9 From 2011-12-07 23:34:26 PST -------
And an unreviewed buildfix landed in http://trac.webkit.org/changeset/102318 ... :(