developed a web page form, in which some data items can only be dropped down and not entered at will, but users can modify the web page code through the debug panel of browser F12, modify the drop-down items into other content at will, and then submit them.
I would like to ask you how to prevent this problem. There seems to be no way through the client. Is it possible that all the drop-down data items can only be checked by the server to see if they are in the legal value? I feel so troublesome. Is there any good idea?