RegExp: with or without "http://"
(?:(?:http|https):\/\/)?([-a-zA-Z0-9.]{2,256}\.[a-z]{2,4})\b(?:\/[-a-zA-Z0-9@:%_\+.~#?&//=]*)?
 
RegExp: /(?:(?:http|https):\/\/)?([-a-zA-Z0-9.]{2,256}\.[a-z]{2,4})\b(?:\/[-a-zA-Z0-9@:%_\+.~#?&//=]*)?/gi
pattern: (?:(?:http|https):\/\/)?([-a-zA-Z0-9.]{2,256}\.[a-z]{2,4})\b(?:\/[-a-zA-Z0-9@:%_\+.~#?&//=]*)?
flags: gi
1 capturing groups: 
   group 1: ([-a-zA-Z0-9.]{2,256}\.[a-z]{2,4})