ruby - Regex to match look before this or that -

ruby - Regex to match look before this or that -

i'm attempting match within of url.

www.facebook.com http://www.facebook.com http://facebook.com

should homecoming facebook

my current regex (?<=www\.|http:\/\/).*(?=\.[a-za-z]{2,4})

this matches correctly except 1 http://www., match www.facebook

how create regex before match lastly occurrence of either wwworhttp://

rubular link

in ruby, can utilize this:

(?i)^(?:http://)?(?:\w+\.)?\k\w+(?=\.[a-z]{2,4}$)

see demo.

^ asserts @ origin of string (?i) puts in case-insensitive mode (?:http://)? optionally matches http:// part (?:\w+\.)? optionally matches subdomain \k keeps out have matched match returned \w+ matches facebook the (?=\.[a-z]{2,4}$) lookahead checks followed domain end of string.

ruby regex