setfocus (control) in asp.net

The code below shows a static method that can be used to easily set focus to a control.

public static void SetFocus(Control control)
{
    StringBuilder sb = new StringBuilder();
 
    sb.Append("\r\n<script language='JavaScript'>\r\n");
    sb.Append("<!--\r\n"); 
    sb.Append("function SetFocus()\r\n"); 
    sb.Append("{\r\n"); 
    sb.Append("\tdocument.");
 
    Control p = control.Parent;
    while (!(p is System.Web.UI.HtmlControls.HtmlForm)) p = p.Parent; 
 
    sb.Append(p.ClientID);
    sb.Append("['"); 
    sb.Append(control.UniqueID); 
    sb.Append("'].focus();\r\n"); 
    sb.Append("}\r\n"); 
    sb.Append("window.onload = SetFocus;\r\n"); 
    sb.Append("// -->\r\n"); 
    sb.Append("</script>");
 
    control.Page.RegisterClientScriptBlock("SetFocus", sb.ToString());
}