Calling Javascript in Dotnet based on Button id

In aspx Page

<script language="javascript" type="text/javascript">
function Getconfirm()
{
var con=confirm("Are sure want to delete this");
var test;
if(con==false)
{
alert("test");
}
else
{
alert("test1");
}
}
</script>

<asp:Button ID="btnsubmit" runat="server" OnClick="btnsubmit_Click" />
In C# Page
protected void Page_Load(object sender, EventArgs e)
{
ScriptManager.RegisterClientScriptBlock(btnsubmit, typeof(string), "bala", "Getconfirm();", true);
}
Note:btnsubmit is control id.