How to match all text between two strings multiline
Solution 1:
Well unfortunately, RegExr is dependent on the JS RegExp implementation, which does not support the option to enable the flag/modifier that you need.
You are looking for the s (DotAll) modifier forcing the dot . to match newline sequences.
- Live Demo on regular expressions 101
If you are using JavaScript, you can use this workaround:
/<!-- OPTIONAL -->([\S\s]*?)<!-- OPTIONAL END -->/