how to get if combobox selected item is null with javascript?

[Amit]

hey everyone,

I want to validate a button such that if combobox selected items count is equal to zero then button click will show an alert on client side. I am doing this:

function filterSearch()
{
  var combo = $find('<%=RadComboBox1.ClientID %>');
  var textbox = document.getElementById("txtSearch");
  var selectedItemsCount = combo.get_selectedItems().length;
  if (selectedItemsCount == 0)
  {
    alert("You must select a category before processing search!");
    return false;
  }
}

This ain't working though. This is my button:

<asp:Button ID="btnSearch" runat="server" Style="float: left; color: black; font-weight: bold" Text="Search" OnClick="btnSearch_Click" OnClientClick="javascript: return filterSearch();" />

How can I do this?

Thanks,
Amit

[Shinu]

Hello Amit,

 Here is code snippet I tried for my application for a similar scenario. I hope this would help you also. 
Here is the code.

Javascript:

function filterSearch()
{
       var combo = $find('<%=RadComboBox1.ClientID %>');
       var textbox = document.getElementById("txtSearch");
       if (combo.get_selectedIndex() == null)
       {

           alert("You must select a category before processing search!");
           return false;
       }
}

Shinu.

[Amit]

Thanks Shinu,that was perfect...

[David]

To resurrect old thread:

if (combo.get_selectedIndex() == null)

gives me an error in Firefox. I tried other solutions with no luck

[Marin Bratanov]

Hi David,

What is the error and its stack trace? I am attaching here a video of my test and this seems to work as expected. What am I missing from your setup and attempts? Can you paste here the combo box markup so I can see how you are using it?

Regards,
Marin Bratanov
Progress Telerik

[David]

Hi Marin,

    Embarrassingly, it works fine now, not sure what happened, likely my bad.

    Sorry to resurrect the issue.

Thank you

David

[Marin Bratanov]

No problem, David, better safe than sorry.

--Marin