Reported here: http://blog.stevenlevithan.com/archives/xregexp-safari. The following regexps are syntax errors in WebKit but not Firefox: /[[\\]/ /[^[\\]/ /[abc[\\]/ "SyntaxError: Invalid regular expression: missing terminating ] for character class"
<rdar://problem/5336079>
This seems to be fixed in the nightlies.