var pw = "ksn73ADkdfdd";
var regex = /^(?=(.*[A-Z]){1})(?=(.*[a-z]){1})(?=(.*\d){1}).{8,15}$/;
// ^.* = start
// (?=(.*[A-Z]){1}) = min. 1 uppercases
// (?=(.*[a-z]){1}) = min. 1 Lowercases
// (?=(.*\d){1}) = min. 1 Numbers
// .{8,15}$ = min. 8 and max. 15 chars
console.log(regex.test(pw));
// source https://stackoverflow.com/a/33051728/4324393