The difference is that the “front end” check itself has nothing to provide for security or a real check. This is a complete performance optimization — a client validation failure saves the circuit on your server, helps to scale, and reduces response time for your users. But the real verification work has to be done on the server side.
ASP.Net validation validation elements help automate server-side validation and synchronize it with the client, while jQuery still requires separate writing of the server logic.
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