How to get selected index from datalist in javascript.

Question

In my code I am adding following code in javascript and datalist

Javascript:
<script type="text/javascript">
$("[id*=Button1]").live("click", function () {
$("#dialog").dialog({
title: "New Name",
buttons: {
Submit: function () {
var item = name.value;
alert("New Name : " + item);

window.open("Page1.aspx?albumname=" + item);

return false;

}
}
});
return false;

});
</script>


Datalist:

<asp:DataList ID="datalist" RepeatDirection="Horizontal" DataKeyNames="val1" RepeatColumns="6" AlternateText=" " runat="server" Height="102px" Width="229px" CellSpacing="5" >
<ItemTemplate >

<asp:TextBox ID="txt" runat="server" Text='<%# Eval("val1") %>' ReadOnly="true" Enabled="false" />
<asp:Button ID="Button1" runat="server" Text="Edit" Height="30" Width="40" AlternateText=" " >

</asp:Button>
</ItemTemplate>

</asp:DataList>

When I click on edit button in datalist then above javascript popup is coming
What I want is when I click on edit button value of textbox associated with it should be also show in alert.
How to show such a value?