regex pattern - what is ((?=.*\d)|(?=.*\W+)) and (?![.\n])

regex

Solution

These are all lookahead assertions (positive and negative) that are making sure the following text respects some rules without actually capturing the text.

               # assert that
(?=^.{8,}$)    # there are at least 8 characters
(              # and
  (?=.*\d)       # there is at least a digit
  |              # or
  (?=.*\W+)      # there is one or more "non word" characters (\W is equivalent to [^a-zA-Z0-9_])
)              # and
(?![.\n])      # there is no . or newline and
(?=.*[A-Z])    # there is at least an upper case letter and
(?=.*[a-z]).*$ # there is at least a lower case letter
.*$            # in a string of any characters

`(?! ... )` is the syntax for a negative lookahead (match if there is no ...), `(?= ... )` is for a positive lookahead (match if there is ...). This looks a lot like password validation!

Problem

Original source