jashkenas--coffeescript/documentation/sections/heregexes.md

Block Regular Expressions

Similar to block strings and comments, CoffeeScript supports block regexes — extended regular expressions that ignore internal whitespace and can contain comments and interpolation. Modeled after Perl’s /x modifier, CoffeeScript’s block regexes are delimited by /// and go a long way towards making complex regular expressions readable. To quote from the CoffeeScript source:

codeFor('heregexes')