Writting my WP-SynHighlight WordPress plugin, I came to a need of parsing multilined shortcode like this:
[ codesyntax option1="optionvalue1"...] <many lines here….> [ / codesyntax]
So, I extracted regular expression to parse shortcode from WordPress source code (if you are interested in it, see /wp-includes/shortcodes.php file). This regex was executed with /s option (PCRE_DOT_ALL) which makes dot (“.”) to match newlines also. There is no such option in JavaScript for some reason and I had to replace dot by such character class:
[\S\s]
Actually, any opposite metacharacters should work. [\W\w] for example.
Quite easy, isn’t it? 
