Pattern di un indirizzo web (URL)

R.F.C. 1738

^(?:(?:http|https|ftp|telnet|gopher|ms\-help|file|notes)://)?(?:(?:[a-z][\w~%!&',;=\-\.$\(\)\*\+]*):.*@)?(?:(?:[a-z0-9][\w\-]*[a-z0-9]*\.)*(?:(?:(?:(?:[a-z0-9][\w\-]*[a-z0-9]*)(?:\.[a-z0-9]+)?)|(?:(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)))(?::[0-9]+)?))?(?:(?:(?:/(?:[\w'~!$=;\-\+\.\^\(\)\|\{\}\[\]]|(?:%\d\d))+)*/(?:[\w'~!$=;\-\+\.\^\(\)\|\{\}\[\]]|(?:%\d\d))*)(?:\?[^#]+)?(?:#[a-z0-9]\w*)?)?$