JavaScript Validation

Question

Hi

  I want if value of Dropdown is Delivered then user must enter Date in Date of Delivery using Javascript

<div class="form-group">
    <label>Status</label>&nbsp;<span style="color: red">*</span>
    <asp:DropDownList ID="ddlStatus" class="form-control" runat="server" required="true">
        <asp:ListItem Value="">Select Status</asp:ListItem>
        <asp:ListItem Value="Return Dispatched">Return Dispatched</asp:ListItem>
        <asp:ListItem Value="Return Delivered">Return Delivered</asp:ListItem>
</div>

Thanks