This is known as AJAX. Asynchronous JavaScript and XML give the user the ability to send information back to the server without any need to load or reload pages.

Here are a couple examples of AJAX to help you along your way. I would suggest tying them with the onchange event. That way, every time an input changes, then you can send the updated information.

W3Schools AJAX
My example - populate textbox with AJAX
My AJAX object