In most languages you can add a modifier to the regex function to change the behavior of the ‘.’ operator so that it matches all characters including new lines (by default it matches everything except new lines). Javascript doesn’t!

This post shows a nifty solution to this problem:
http://siphon9.net/loune/2011/02/match-any-character-including-new-line-in-javascript-regexp/

EDIT:

Turns out this trick doesn’t work in IE. Here is another one that is supported by IE and apparently all other browsers: Use [\s\S] instead.

http://simonwillison.net/2004/Sep/20/newlines/