My password strength criteria is as below :
8 characters length No Special Characters Atleast 1 numeral Atleast 1 alphabet
Try this:
^(?=.*\d)(?=.*[a-zA-Z]).{8,}$
or
^(?=.*\d)(?=.*[a-zA-Z])(?!.*[\W_\x7B-\xFF]).{8,}$
The first does not care about special characters, the second disallows them.