How to get its old value when input is changed?

Question

JavaScript

Actually, there is an input that changes. Getting a new input value is not difficult, but I can’t figure out how to get the old value that was before entering the new one. Maybe some other event should be used?

var price = $('#product-price').val(),
          width = $('#product-width').val();

      $('#product-footage').keyup(function(){
        var footage = $('#product-footage').val();

        // 
      });

Answer 1

you can store the previous value in the data attribute when you get focus on the element.
implementation example

Answer 2

Might be worth using keydown. Then event.target.valueit will store the previous value, and event.keythe input character.