\s*any whitespace character, repeated any number of times
Non-Capturing Group(?:Joker(?:\s+|$))* *repeats the group contents below any number of times:
Jokerthe literal text Joker (case sensitive) Non-Capturing Group(?:\s+|$) \s+any whitespace character, repeated at least once
(*SKIP)acts like (*PRUNE), but the next unanchored match attempt starts where (*SKIP) was reached instead of at the next subject character
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
.any character (except for line terminators)
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string