<asp:Button runat="server" OnClientClick="alert('클릭!');" />

<asp:Button runat="server" OnClientClick="return confirm('진짜?');" />

protected void Page_Load(Object sender, EventArgs e)

{

System.Text.StringBuilder sb = new System.Text.StringBuilder();

sb.Append("<script language='javascript' type='text/javascript'>alert('클릭');</script>");

ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", sb.ToString());

}

Response.Write("<script type='text/javascript'>alert('t is null')</script>");

                System.Text.StringBuilder sb = new System.Text.StringBuilder();

                sb.Append("<script language='javascript' type='text/javascript'>alert('t 는 널 입니다.');</script>");

                ClientScript.RegisterStartupScript(this.GetType(), "alert", sb.ToString());

                ClientScript.RegisterClientScriptBlock(typeof(string), "confirm", sb.ToString());