Not very secure.js

/*
Description:
In this example you have to validate if a user input string is alphanumeric. The given string is not nil/null/NULL/None, so you don't have to check that.

The string has the following conditions to be alphanumeric:

At least one character ("" is not valid)
Allowed characters are uppercase / lowercase latin letters and digits from 0 to 9
No whitespaces / underscore
*/
function alphanumeric(string){
  return /[a-zA-Z0-9]/g.test(string)&&!/[\s_!]/.test(string)
}