AjaxControlToolkit.ScriptControlBase.EnsureScriptManager C# (CSharp) Method

        void EnsureScriptManager()
        {
            if(_scriptManager == null) {
                _scriptManager = ScriptManager.GetCurrent(Page);
                if(_scriptManager == null)
                    throw new HttpException("A ScriptManager is required on the page to use ASP.NET AJAX Script Components.");
            }
        }