Lookahead regex not works

[vfa-namnk]

Thanks for the library. With /^(?=.*[A-Za-z])(?=.*\d)[A-Za-z\d]{8,}$/, I would like to generate random string: minimum eight characters, at least one letter and one number, however it returns DgxrCkquz which contains no number.

Similar issue: fent/randexp.js#18