Validation for Date of birth and Date of Joining.

Hi,
I have two textbox where I want to add validations for the textboxes on button submit. I want that Date of birth should not be greater than date of joining. How it can be achieved in javascript. Or please let me know what would be easy step. Please see the html's for both the textboxes.
<asp:TextBox ID="txtdateofbirth" CssClass="form-control" runat="server" ValidationGroup="AddNew"></asp:TextBox> <asp:TextBox ID="txtdoj" CssClass="form-control" runat="server" ValidationGroup="AddNew"></asp:TextBox> Please help