quackbarc

\b(?:(?<fizzbuzz>(?:(?:[369]|[258][0369]*[147]|(?:[147]|[258][0369]*[258])(?:[0369]|[147][0369]*[258])*(?:[28]|[147][0369]*[147]))*(?:0|(?:[147]|[258][0369]*[258])(?:[0369]|[147][0369]*[258])*5))+)|(?<buzz>\d*[05])|(?<fizz>(?:[0369]|[258][0369]*[147]|(?:[147]|[258][0369]*[258])(?:[0369]|[147][0369]*[258])*(?:[258]|[147][0369]*[147]))+))\b

insanity, as i'd like to call it. although it isn't fizzbuzz per se, it's the best you can get with regex. here's a regexr link to it with sample text.

this matches a number (within word boundaries) if it falls under any of the three groups:

• fizzbuzz, which picks up numbers divisible by both 3 and 5, i.e. 15;
• buzz, which picks up numbers divisible by 5; and
• fizz, which picks up numbers divisible by 3.