how to detect duplicate value selected in dropdown using javascript or jquery?
<p><img src="http://i.stack.imgur.com/PjyKD.png" alt="enter image description here">i have a gridview inside a repeater, and a dropdownlist insid the gridview. now i want no user can select one value twice.my code is </p>

<pre><code>&lt;asp:Repeater ID="rep_test" runat="server"&gt;
    &lt;ItemTemplate&gt;
       &lt;asp:GridView ID="grd_test" runat="server" Style="text-align: center;
                width: 375px;" AutoGenerateColumns="false"&gt;
                &lt;Columns&gt;
                    &lt;asp:BoundField HeaderText="hello" DataField="hello" /&gt;
                &lt;/Columns&gt;
                &lt;Columns&gt;
                    &lt;asp:BoundField HeaderText="item" DataField="item" /&gt;
                &lt;/Columns&gt;
                &lt;Columns&gt;                        
                    &lt;asp:TemplateField HeaderText="Assign to"&gt;
                        &lt;ItemTemplate&gt;
                            &lt;asp:DropDownList ID="drp_Assign" runat="server"&gt;
                                &lt;asp:ListItem Value="1"&gt; 1&lt;/asp:ListItem&gt;
                                &lt;asp:ListItem Value="2"&gt;2&lt;/asp:ListItem&gt;
                                &lt;asp:ListItem Value="3"&gt;3&lt;/asp:ListItem&gt;
                            &lt;/asp:DropDownList&gt;
                        &lt;/ItemTemplate&gt;
                    &lt;/asp:TemplateField&gt;
                &lt;/Columns&gt;
            &lt;/asp:GridView&gt;
            &lt;asp:DropDownList ID="drp_Address" runat="server"&gt;
            &lt;/asp:DropDownList&gt;
    &lt;/ItemTemplate&gt;
&lt;/asp:Repeater&gt;
</code></pre>

<p>i want to detect the duplicate value for drodown "drp_Assign". </p>

<p>please see the image the values in comp number should not be duplicate if a user selected "1" for one row then he will not be able to selected same value in second row . if he tries to do then alert message will be shown that you have selected this value already choose another."</p>
