Edit:
The OP commented: This was just a typo in the question, not actually in the code
onOnClientClick
should be
OnClientClick
Edit:
Attempt 2.
The client click will not do much because the page is being posted anyway. Instead of OnClick="Button1_Click" try this (or similar)
<asp:Button ID="Button1"
runat="server" Text="save"
onOnClientClick="uservalid(this);"/>
<script ...>
function uservalid(control){
controle.preventDefault();
bool isValid = someotherstuff();
if(isValid)
__doPostBack(control.id,null);
}
</script>
This is not tested but I've done similar before. The postback function should cause the click event to be triggered.
You will still have to wire up the click event in the code behind but have autopostback = false so the for is only posted if the user validation passes