Once upon a time in Denmark some invented the CPR giving every legal person i the country a 10 digit identification number. The number, of course is a 6 digit birthday, ddmmyy, followed by a 4 digit serial number, ending in an even digit if you are a woman, and in an odd digit if you are a man.

Let us discuss ways of validating the input, and having reached some clarity, you put the code into the JavaScript file, and test it.

Let us also discuss email addresses syntactically. What are the rules? Who decides? How do we check? Can they be checked 100% for validity?

Having reached some clarity everybody codes and introduces the code into the JavaScript file. Test again of course.

You have done this before, in PHP? Look back and learn.