ASP.net Postback - Scroll to Specific Position

Question

I have an ASP.net WebForms page that has a lot of content on the top of the screen. It has a link button that will post back to the page and show another section of the page

Answer 1

While not elegant for your situation, it is also possible to use dummy Custom Validators, set the one you want to scroll to as invalid then do

DummyCustomValidator.SetFocusOnError = true;

In my case, I am actually using page Validators with async postbacks and multiple programmatically shown/hidden panels on a long vertical form. Since some fields are only required if MyLogicalParent.Visible = true and if specific answers are given in other controls, such as a RequiredFieldValidator on a TextBox when "Other" is selected in a CheckBoxList, I have a LOT of logic to process page validation. Setting scroll positions was painful in all of the normal methods.

I also use RegisterStartupScript to handle maintaining the current scroll position when async postbacks alter the page's vertical dimension.

    

     <%-- This stores the Y scroll location.--%>
        
        

            Scroll down for more.
        





 private string LastScrolled = "";

    protected void Page_PreRender (object sender, EventArgs e)
            {
                if (string.IsNullOrEmpty(LastScrolled))
                {
                    LastScrolled = "0";
                }
                if (string.IsNullOrEmpty(scrollPosition))
                {
                    sb.Clear();
                    sb.AppendLine("Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);");
                    sb.AppendLine("function EndRequestHandler(sender, args) {");
                    sb.Append("scrollTo(0, ").Append(LastScrolled).Append(");");
                    sb.AppendLine("}");
                    sb.AppendLine("function load() {");
                    sb.AppendLine("Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);");
                    sb.AppendLine("}");
                    cs.RegisterStartupScript(GetType(), "ScrollToLastPosition", sb.ToString(), true);
                    scrollPosition = "ScrollToLastPosition";
                }
                if (!string.IsNullOrEmpty(scrollPosition))
                {
                    ScriptManager.RegisterStartupScript(this, GetType(), scrollPosition, sb.ToString(), true);
                }
            }

    protected void Page_Load (object sender, EventArgs e)
            {
              LastScrolled = HF_LastScrolled.Value;
              Page.MaintainScrollPositionOnPostBack = false;
            }

   protected void SetScrollToLastPosition ()
            {
                sb.Clear();
                sb.AppendLine("Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);");
                sb.AppendLine("function EndRequestHandler(sender, args) {");
                sb.Append("scrollTo(0, ").Append(LastScrolled).AppendLine(");");
                sb.AppendLine("}");
                sb.AppendLine("function load() {");
                sb.AppendLine("Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);");
                sb.AppendLine("}");
                cs.RegisterStartupScript(GetType(), "ScrollToLastPosition", sb.ToString(), true);
                scrollPosition = "ScrollToLastPosition";
                string tempstring = sb.ToString();
                ScriptManager.RegisterStartupScript(this, GetType(), scrollPosition, sb.ToString(), true);
            }

protected void SetScrolltoPositionY (int y)
            {
                sb.Clear();
                sb.AppendLine("Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);");
                sb.AppendLine("function EndRequestHandler(sender, args) {");
                sb.Append("scrollTo(0, ").Append(y).AppendLine(");");
                sb.AppendLine("}");
                sb.AppendLine("function load() {");
                sb.AppendLine("Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);");
                sb.AppendLine("}");
                cs.RegisterStartupScript(GetType(), "ScrollTo-0-" + y.ToString(), sb.ToString(), true);
                scrollPosition = "ScrollTo - 0-" + y.ToString();
                string tempstring = sb.ToString();
                ScriptManager.RegisterStartupScript(this, GetType(), scrollPosition, sb.ToString(), true);
            }