as per the title; is it possible to have nested comments in valid HTML? see the example below...
<p>some text</p>
<!-- comment 1
<p>commented out html</p>
<!-- comment 2
// are nested html comment allowed?
end of comment 2 -->
<p>more commented out html</p>
end of comment 1 -->
<p>some more text</p>
It appears not, does anybody know how I could get nested comments to work?
TL;DR: Unfortunately, no, it's not possible (and never will be).
Short answer:
An HTML comment is not quite what many think it is. HTML is a form of SGML, in which comments are delimited by pairs of double-dashes (-- … --).
Thus, any pair of a double-dashes inside a pair of angle brackets with an exclamation point after the opening bracket (<! -- ⋯ -- >) is a comment. The spec says it better than I can: http://www.w3.org/TR/html4/intro/sgmltut.html#h-3.2.4
This is why comments like this one (which we've all likely done one time or another) are a bad idea:
<!-- ------------------ HEADER BEGINS HERE -------------------- -->
Truth: I am too lazy to tell you how many comments are represented by the above tag pollution, but it's at least 10.
I got less lazy: This so-called "comment" actually consists of 10 comments, three words outside any comment (i.e., just bad SGML), and the beginning of a comment that is not terminated. It's a real mess:
<!--1----2----3----4----5-- HEADER BEGINS HERE --6----7----8----9----10-- -->
Of course, it's not quite that simple, due to differences in how each browser chooses to interpret the spec.
Here's an excellent article that explains it:
http://weblog.200ok.com.au/2008/01/dashing-into-trouble-why-html-comments.html