Asp.net: Disable button after click and display text

        protected void Page_Load(object sender, EventArgs e)
        {
            button.Attributes.Add("onclick", string.Format("if(typeof(Page_ClientValidate)=='function' && !Page_ClientValidate()){return false;}this.value='wait...';this.disabled=true;{0}",
                ClientScript.GetPostBackEventReference(button, string.Empty)));
        }
        protected void ButtonClick(object sender, EventArgs e)
        {
            //in every postback event method
            Page.ClientScript.RegisterOnSubmitStatement(GetType(), "ServerForm","if(this.submitted) return false; this.submitted = true;");
        }