Regex for password: repetative characters

Question

I have following conditions for password validation.

Password must be at least eight (8) characters in length. Password must contain both alpha and numeric characte

Answer 1

How about

(?>([a-zA-Z])(?!\1)){8,}

Answer 2

The regex to match repeated characters is /(.)\1/.
I would simply do this as a two-step verification, no need to roll it into one regex.
As pointed out in the comments, this only lowers password entropy and thereby security though.

Answer 3

Thanks ..got answer ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*(.)\1).{8}$

Answer 4

Look aheads are your friend:

^(?=.*\d)(?=.*[a-zA-Z])(?!.*(.)\1).{8,}