RegEx String, 12 signs (at least 1 number and at least 1 letter)

Question

I have problems with RegEx. How do I get an 12 signs long part of a string which contains at least 1 number and 1 letter?

Example: \"This is 12 signs long:

Answer 1

To find an alphanumeric word of length 12 within a longer text, use

(?i)              # Case-insensitive matching
\b                # Start of word
(?=[A-Z]*[0-9])   # Assert presence of at least one ASCII digit
(?=[0-9]*[A-Z])   # Assert presence of at least one ASCII letter
[A-Z0-9]{12}      # Match exactly 12 ASCII letters/digits
\b                # End of word

or (for JavaScript, because it doesn't support verbose regexes)

/\b(?=[A-Z]*[0-9])(?=[0-9]*[A-Z])[A-Z0-9]{12}\b/i