let re=/^(?=.*[A-Za-z])(?!.{16,})([A-Za-z'-]*[\s]?[A-Za-z'-]*)$/The above regular expressions will feel strange compared to the first encounter with children's shoes. Let me explain here.
I checked some information. This? =,?! Writing is actually a pre-judgment writing, which needs to be wrapped in parentheses.
For example,? =. * [A-Za-z]) This part is to first judge whether this string conforms to the format of *. [[A-Za-z], if it does, continue to go down, otherwise it returns false directly;
And?! Is to first determine whether it does not meet, continue if it does not match, return false;
The advantage of writing in this way is that it does not occupy character space, the logic is more clear, and the overall analysis can be performed.
example:
(? =. * [0-9]) there is a number after any string (? =. * [Az]) there is a lowercase letter after any string (? =. * [AZ]) there is a capital letter after any string
