Question

I want to get all the listitems that exist in a listbox using jquery, it does not matter if selected or not.

Here is my client side script:

<asp:ListBox ID="lstSelected" runat="server" SelectionMode="Multiple" Rows="10">
    <asp:ListItem Value="Employee_OID">EID</asp:ListItem>
    <asp:ListItem Value="EmpID">Emp ID</asp:ListItem>
    <asp:ListItem Value="Employee_Name">Name</asp:ListItem>
</asp:ListBox>

Answer 1

By adding a static ID (ClientIDMode=”Static”) generation to the ListBox, you could use the ID property value in jQuery directly (skipping ClientID usage):

<asp:ListBox ID="lstSelected" runat="server" SelectionMode="Multiple" Rows="10" ClientIDMode="Static">
    <asp:ListItem Value="Employee_OID">EID</asp:ListItem>
    <asp:ListItem Value="EmpID">Emp ID</asp:ListItem>
    <asp:ListItem Value="Employee_Name">Name</asp:ListItem>
</asp:ListBox>

jQuery to get all options:

$('#lstSelected option')

jQuery to get all selected options:

$('#lstSelected option:selected')

See more info here on the ClientIDMode:
http://msdn.microsoft.com/en-us/library/system.web.ui.control.clientidmode.aspx