Question

This is what I’ve started out with and it only changes input#user_name upon running the script. How do I get it to live update the value?

var $username = $("input#user_email").val();

$("input#user_name").val($username);

Answer 1

$("input#user_email").keyup(function(){
  $("input#user_name").val($(this).val());
});

if what you mean is that when you type on user_email you want that on user_name