Validating date using Compare Validator asp net

Use below given code snippet

<asp:CompareValidator ID="CompareValidator1" runat="server" ErrorMessage="Invalid Date"  

Operator="DataTypeCheck" Type="Date" ControlToValidate="{}" ControlToCompare="not required">

</asp:CompareValidator>

Export / Output asp net gridview output to excel file

If you want to export gridview output to an excel file you can use the following code.
In this example it is done by clicking a button
Requirements

1. GridView with ID GridView1
2. ASP NET Button With ID Button1

   protected void Button1_Click(object sender, EventArgs e)
   {
       string filename = "Bingo.xls";
       ExportToExcel(filename, GridView1);
   }
    
   private void ExportToExcel(string filename, GridView gv)
   {
       Response.ClearContent();
       Response.AppendHeader("content-disposition", "attachment; filename=" + filename);
       Response.Charset = "";
       Response.Cache.SetCacheability(HttpCacheability.NoCache);
       Response.ContentType = "application/vnd.ms-excel";
       System.IO.StringWriter stringWriter = new System.IO.StringWriter();
       HtmlTextWriter htw = new HtmlTextWriter(stringWriter);
       gv.RenderControl(htw);
       Response.Write(stringWriter.ToString());
       Response.End();
   }

Half way there Don't forget to override VerifyRenderingInServerForm

public override void VerifyRenderingInServerForm(Control control)
{
    /* Verifies that the control is rendered */
}

All done.

How to disable jQuery UI tab(s)

Single tab

$( "#tabs" ).tabs( "option", "disabled", 1);

Multiple tabs

$( "#tabs" ).tabs('option','disabled', [1, 2, 3, 4]);

An entry with the same key already exists.

Causes:

• Multiple asp net controls with same ID
• Mostly occurs inside ListView control 
• Try using different ID's for control in insertitem template and edititemtemplate.
• or just hide insertitemtemplate when edititemtemplate is active.
• Keep an eye on validator controls. Try to have different id on master and child pages.

Change an Image while using JCrop

Initialize jCrop

var jcrop_api;
        function InitjCrop() {
            $('#id').Jcrop({  }, function () {
                jcrop_api = this;
            });
        }

To unhook jCrop

jcrop_api.destroy();

To Hook jCrop again

InitjCrop();