Hello I'm trying to solve the classic rotational cypher problem but im also trying to solve for when numbers are included in the string. So far this is the method I have been going about it using javascript:

function rotationalCipher(input, rotationFactor) {

const originalAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

return input.replace(/[a-z]/gi, letter => originalAlpha[originalAlpha.indexOf(letter)+rotationFactor]);
  

}

It works but it doesn't address the numbers within the string. Id be appreciative of any help.