Regex pattern to match at least 1 number and 1 character in a string

This RE will do:

/^(?:[0-9]+[a-z]|[a-z]+[0-9])[a-z0-9]*$/i

Explanation of RE:

• Match either of the following:
  1. At least one number, then one letter or
  2. At least one letter, then one number plus
• Any remaining numbers and letters
  
  
• (?:...) creates an unreferenced group
• /i is the ignore-case flag, so that a-z == a-zA-Z.

Why not first apply the whole test, and then add individual tests for characters and numbers? Anyway, if you want to do it all in one regexp, use positive lookahead:

/^(?=.*[0-9])(?=.*[a-zA-Z])([a-zA-Z0-9]+)$/