I am trying to use this regex (JS):
/\/\*(.*)\*\//g
To replace
/*
sdandsads
*/
with nothing.
But it is not working! Why? o_O
There's no `s` (single-line) mode in JavaScript, and `(\s|.)` courts catastrophic backtracking. The standard way to match anything-including-newlines in JS is `[\S\s]`.
Alan Moore
2010-03-17 01:58:26
@alan, any links about the `\s|.` backtracking ? would like to learn more about it..
Gaby
2010-03-17 02:35:02
Erik Corry explained it well here: http://stackoverflow.com/questions/2407870/javascript-regex-hangs-using-v8/2408599#2408599 For a more general discussion of catastrophic backtracking, see http://www.regular-expressions.info/catastrophic.html
Alan Moore
2010-03-17 13:55:43
wow, pretty obvious once you consider that regexp has to be applied somehow, and it is not just a rule and a result :) thanks for the links @Alan
Gaby
2010-03-17 14:25:32
+3
A:
Two problems:
- In javascript, there's no dotall modifier. You'll have to use a hack to allow matching newlines, such as using
[^]. - You're using greedy matching. If there are multiple comments in your input, everything between them will be eaten.
Solution:
/\/\*[^]*?\*\//g
Example:
> '/*abc\ncde*/qqq/*iop\n\njj*/'.replace(/\/\*[^]*?\*\//g, '')
qqq
Max Shawabkeh
2010-03-16 23:14:52