The .valid() function checks whether the form is valid. In .net world, you can add a "OnClientClick" event to your submitting events that "returns" true or false for the validity of the form.
<asp:Button runat="server" id="btnFormUpdate" Text="Update" OnClientClick="return isValid()" />
<script>
function isValid() {
var v = $("#form1").valid();
return v;
}
</script>
This setup will prevent the button from executing the click event based on the validity of the form.