[yesbabyyes]

I agree. I'm pretty sure jashkenas got it from Ruby, which got it from Perl, with the `/x` flag (for extended regular expressions).

Later languages have added support for the `x` flag, including C# and Rust. There is also a stage 1 proposal for JavaScript: https://github.com/tc39/proposal-regexp-x-mode

[loginx]

Nice roundup, and thanks for sharing that proposal!

[genewitch]

Notepad++ has /x mode as well.

I probably use regexes the most in notepad++