Ever since xmlhttprequest (and even before that with images) we've been able to do server-side validation without a full page reload.
This "solution" completely ignores the purpose of client-side validation which is to a) reduce load on server-side resources, b) validate faster without the network latency and c) validate more securely and privately by not sending the content to the server.
This "solution" completely ignores the purpose of client-side validation which is to a) reduce load on server-side resources, b) validate faster without the network latency and c) validate more securely and privately by not sending the content to the server.