How to get the selected value from ajax.net ComboBox through javascript

I need to get the selected value from an ajax.net combobox throught javascript so that I can do some client side validation.

What's the best way to do this? Thanks,

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I've been able to get the value with this:

var combo = $get('ddlComarcas');
var comboHidd开发者_如何学编程en = $get('ddlComarcas_HiddenField');
var o4 = combo.getElementsByTagName('li')[comboHidden.value].childNodes[0];

alert('"' + o4.data + '"');

But I still need to trim the value from o4.data. Anyone can point how to do that visual studio 2008 jquery?

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You can use jQuery or just use DOM:

jQuery:

var selection = $('#selectID').val();

DOM:

var selection = document.getElementById("selectID").value;

asp.net -> server side

javascript -> client side

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I think the answer is value doesnt exist client side so it cant be retrieved. There are easier ways to get index tho (assuming whatever initialization is complete).

selected index:         $find("<%=cboName.ClientID%>").get_hiddenFieldControl().value;
selected index (again): $find("<%=cboName.ClientID%>").get_selectedIndex();
selected text:          $find("<%=cboName.ClientID%>").get_textBoxControl().value;

As far as I can tell, validating a combobox on the client requires some faith in index or text, or some kind of server side workaround.

To provide a direct answer to the subject line, a javascript array could be created server side with each combobox value and then referenced client side by selected index...

codebehind:

 // write combobox values to asp:literal
 foreach (ListItem i in cboName.Items)
         litCboValues.Text += "\"" + i.Value.Replace("\"", "\\\"") + "\", ";
 litCboValues.Text = litCboValues.Text.TrimEnd(new char[] {',', ' '});

aspx:

<script>
// array of values
 var cboValues = [ <asp:Literal id="litCboValues" runat="server" /> ];

// add an alert to the combobox to test
function pageLoad()
{
  $find("<%=cboName.ClientID%>").get_textBoxControl().onblur = function () { 
    alert( cboValues[$find("<%=cboName.ClientID%>").get_selectedIndex()] );
  };
}
</script>


<asp:ComboBox id="cboName" runat="server" ...

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this works (today) in IE and Chrome - about the only thing ie is good for is the debugger f12 (- you can browse through the watched objects

Following // i do it on button but you could probably do it on a combo event Follow

 function addFollowed() {
      var combo = $get('<%= FollowListBox.ClientID %>'); 
      var toFollow = combo.control._textBoxControl.value;