165323 - unclosed comment problem in strict mode with document.write()

Status: RESOLVED INVALID

(Core :: DOM: HTML Parser, defect)

Description

[Peter Brennan]

Hi.

When using Mozilla 1.1 or Netscape 7, I have a problem with document.write.

When I try to use document.write() to output "<!--", the <! is removed, and 
only "--" is written.  If I insert another space, it outputs "< !--" just 
fine.  

document.write("<!--") works fine in IE, NS4.77, NS6, Opera, etc.  We use this 
for a dynamic hiding technique like:

<script type="text/javascript">
if (something) {
     document.write("<!-- hide");
}
</script>

....stuff

<!--  -->

Any thoughts?

Peter Brennan
[e-mail]

Comment 1

[Phil Schwartau]

Browser, not engine ---> DOM Level 0

Comment 2

[Boris Zbarsky [:bzbarsky]]

Attachment: testcase (quirks mode)

I cannot reproduce the problem with this testcase.

Comment 3

[Boris Zbarsky [:bzbarsky]]

Attachment: testcase (standards mode)

I _do_ see the problem in this case.

Comment 4

[Boris Zbarsky [:bzbarsky]]

Attachment: Testcase in standards mode with properly terminated comment

Comment 5

[Boris Zbarsky [:bzbarsky]]

Attachment: Testcase, standards mode, static document, unterminated comment.

Comment 6

[Boris Zbarsky [:bzbarsky]]

Looks like standards comment parsing tries to deal with the unterminated comment
somehow and fails...  Over to parser.

Comment 7

[Heikki Toivonen (remove -bugzilla when emailing directly)]

Hmm, this is somewhat intended. Forget DHTML for now, and think about a static
page. In a page we see "<!--", but no comment close. We understand that as "no
comment", and treat treat everything from "<!--" (inclusive) as text. (There is
a bug that we actually eat the "<!".)

With document.write() we then have the problem that if you do several write()
operations where one contains "<!--" but not comment close, what should we do?
As you noted, we don't treat it as a comment at all. We just won't know which
document.write() is going to be the last one.

We cannot change the way we do parsing of static strict pages, because we know
that would break sites (hide a lot of content).

I am not sure what would be a good way to fix it for document.write().
Everything I can think of seems very difficult to do with high risk of
regressions. The gain seems minimal, since pages that run into this could be
written in other ways.

What real sites are there that break because of this?

Comment 8

[Boris Zbarsky [:bzbarsky]]

*** Bug 186537 has been marked as a duplicate of this bug. ***

Comment 9

[Ruslan Ismailov]

Attachment: This is example of this bug in real life

Every cite, that use this counter and have strict mode affected by this one. My
own was affected (well... I solve this problem by changed js>11 to 11<js -- and
now it at least terminated). 

I don't know any other standart compilant cite with this counter, I found one:

http://www.pereplet.ru/

Comment 10

[Blake Kaplan (:mrbkap) (inactive)]

I'm not sure this is a bug, actually. What happens is that we try to parse the
comment in strict mode, but the document looks like this:

<!-- blah....

  <!--  --> more content etc...

So, removing extraneous characters and whitespace, we are looking at: |<!-- --
-->| which is an unterminated comment. So we try to parse it as text, and end up
losing the "<!" (which is a known bug) and parsing the comment as text. Am I
missing anything here, or is this INVALID?

Comment 11

[Blake Kaplan (:mrbkap) (inactive)]

Marking INVALID per my last comment. I'll bet this regressed (as I see the
regression keyword) when we enabled strict comment parsing, but that's just a guess.