Help with web-code

Question

In my code I have some forms with text inputs, and I need to look for it changes. So if value in first input changes, something must happen. For example, alert()

Please make it.
https://code.sololearn.com/Wpc9ibZMoL2d/?ref=app

Answer 1

Thank, but I just need function on something else, I need the code

Answer 2

What you want to do. I dont know how yet, but I will finish code by myself. You can just make: alert("Changed value of" + id_of_HTML_element_where_value_changed)