javascript multiline regexp replace

Question

"foo\r\nbar".replace(/(foo).+/m, "bar")

Hello. I can not understand why this code does not replace foo on bar

Tomalak · Accepted Answer · 2015-10-30T15:34:10.527

39

I can not understand why this code does not replace foo on bar

Because the dot . explicitly does not match newline characters.

This would work:

"foo\r\nbar".replace(/foo[\s\S]+/m, "bar")

because newline characters count as whitespace (\s).

Note that the parentheses around foo are superfluous, grouping has no benefits here.

edited Oct 30 '15 at 15:34

answered Apr 04 '10 at 20:34

Tomalak

Thanks, I didn't know. In ruby it does by default. – Andrey Kuznetsov Apr 04 '10 at 20:37
7

`[\s\S]` is a much better workaround than `(?:.|\s)`; see Erik Corry's answer to this question for the reason: http://stackoverflow.com/questions/2407870/javascript-regex-hangs-using-v8 – Alan Moore Apr 04 '10 at 22:12

score 24 · Answer 2 · answered Apr 04 '10 at 20:34

24

JavaScript does not support a dot-all modifier. A common replacement is:

"foo\r\nbar".replace(/(foo)[\s\S]+/, "bar")

/m makes ^ and $ behave correctly, but has not effect on ..

answered Apr 04 '10 at 20:34

Kobi

2 Answers2