Tags:
create new tag
, view all tags

Bug: Heading isn't included within <a name...> </a> HTML tags if text contains 3 or more successive caps

A bizarre bug this, but one that is annoying in the context in which I am using TWiki. It is best illustrated by the test case shown below.

The reason why it is annoying is:

  • We are using bold blue for links within TWiki docs changing to red-underline on hover. This is the corporate style.

  • This bug variously renders the text either in blue, if enclosed within the <a name...> tag, or black if it isn't. So, the end-user sees a mixture of blue and black headings in topics: blue so long as a heading contains fewer than 3 consecutive capital letters, and black if it contains more than 3!

Ideally, we'd like the style of the text at each heading level to be defined purely by the corresponding <h1>, <h2>, <h3>, etc, tags. Instead, it is arbitrarily being defined by the <a name...> tag or by the <h?> tag.

Test case

(The colour has been added manually to represent how the text appears on our TWiki site)

The following heading is included fully within the <a name...> </a> tags and hence takes its formatting from the <a> tag:

This is an included heading

The corresponding HTML code generated by TWiki is:

    <h3><a name="This_is_an_included_heading"> This is an included heading </a></h3>



This next heading is excluded from the <a name...> </a> tags and hence takes its formatting from the <h3> tag.

This is an EXCluded heading

The corresponding HTML code generated by TWiki is:

    <h3><a name="This_is_an_EXCluded_heading"> </a> This is an EXCluded heading </h3>

Environment

TWiki version: Athens (Dec 2001)
TWiki plugins: Default, Smilies, Interwiki
Server OS: SuSE Linux 8
Web server: Apache
Perl version: 5.6.1
Client OS: Win2k
Web Browser: IE5.5

-- RichardLewis - 01 Oct 2002

Follow up

This topic would be better named "InconsistentHandlingOfHeadings".

Having delved into TWiki.pm I've found the following in sub makeAnchorHeading :

    my $hasAnchor = 0;  # text contains potential anchor
    $hasAnchor = 1 if( $text =~ m/<a /i );
    $hasAnchor = 1 if( $text =~ m/\[\[/ );

    $hasAnchor = 1 if( $text =~ m/(^|[\s\(])([A-Z]{3,})/ );
    $hasAnchor = 1 if( $text =~ m/(^|[\s\(])([A-Z]+[a-z0-9]*)\.([A-Z]+[a-z]+[A-Z]+[a-zA-Z0-9]*)/ );
    $hasAnchor = 1 if( $text =~ m/(^|[\s\(])([A-Z]+[a-z]+[A-Z]+[a-zA-Z0-9]*)/ );
    if( $hasAnchor ) {
        # FIXME: '<h1><a name="atext"></a></h1> WikiName' has an
        #        empty <a> tag, which is not HTML conform
        $text = "<nop><h$theLevel><a name =\"$anchorName\"> </a> $theText <\/h$theLevel>";
    } else {
        $text = "<nop><h$theLevel><a name =\"$anchorName\"> $theText <\/a><\/h$theLevel>";
    }

    return $text;
The purpose of this code is to ensure that the subroutine doesn't accidentally create illegal nested <a> statements. However, it also introduces the heading handling inconsistency described in this bug report.

The simple solution I have adopted is to set $hasAnchor = 1 at all times, ensuring that headings always sit outside of the <a> </a> tags and therefore take their formatting from the appropriate <h> tag.

Incidentally, although the comment in the subroutine says that an empty <a> tag is non-HTML conformant this doesn't seem to be true in HTML4 - at least not according to w3.org (see http://www.w3.org/TR/REC-html40/struct/links.html) which merely states:

Note. User agents should be able to find anchors created by empty A elements, but some fail to do so. For example, some user agents may not find the "empty-anchor" in the following HTML fragment:

<A name="empty-anchor"></A>
<EM>...some HTML...</EM>
<A href="#empty-anchor">Link to empty anchor</A>

-- RichardLewis - 08 Oct 2002


I ran into the same problem when I installed the GnuSkin skin (the version compatible with BeijingRelease), since that skin uses a style sheet setting that colors all links. The result is just as described above--very disconcerting.

-- MarkBearden - 17 Mar 2003


Fix record

Edit | Attach | Watch | Print version | History: r3 < r2 < r1 | Backlinks | Raw View | Raw edit | More topic actions
Topic revision: r3 - 2003-03-17 - MarkBearden
 
  • Learn about TWiki  
  • Download TWiki
This site is powered by the TWiki collaboration platform Powered by Perl Hosted by OICcam.com Ideas, requests, problems regarding TWiki? Send feedback. Ask community in the support forum.
Copyright © 1999-2017 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.