#JS, #RegExp: How To Validate Password With Regular Expression

script.js

// 1. approach:
((?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{6,20})

/*

(			# Start of group
  (?=.*\d)      #   must contains one digit from 0-9
  (?=.*[a-z])		#   must contains one lowercase characters
  (?=.*[A-Z])		#   must contains one uppercase characters
  (?=.*[@#$%])  #   must contains one special symbols in the list "@#$%"
            .		#     match anything with previous condition checking
      {6,20}    #        length at least 6 characters and maximum of 20	
)

*/

// via From http://www.mkyong.com/regular-expressions/how-to-validate-password-with-regular-expression/


// 2. approach:
^(?=.*[A-Z].*[A-Z])(?=.*[!@#$&*])(?=.*[0-9].*[0-9])(?=.*[a-z].*[a-z].*[a-z]).{8}$

/*
^                         Start anchor
(?=.*[A-Z].*[A-Z])        Ensure string has two uppercase letters.
(?=.*[!@#$&*])            Ensure string has one special case letter.
(?=.*[0-9].*[0-9])        Ensure string has two digits.
(?=.*[a-z].*[a-z].*[a-z]) Ensure string has three lowercase letters.
.{8}                      Ensure string is of length 8.
$                         End anchor.
*/

// via http://stackoverflow.com/questions/5142103/regex-for-password-strength