Compare dates selected by jQuery DatePicker TextBoxes on Button click in ASP.Net

I have used Compare validation here as per your requirement

OnlineApplicationStartDate < OnlineApplicationEndDate 

And

OnlineApplicationEndDate < OnlineApplicationEditDate

HTML

Online Application Start Date
<asp:TextBox ID="txtOnlineApplicationStartDate" runat="server" />
<asp:CompareValidator runat="server" ControlToValidate="txtOnlineApplicationStartDate"
    ControlToCompare="txtOnlineApplicationEndDate" Operator="LessThan" Type="Date"
    Display="Dynamic" ValidationGroup="OnlineApplicationDate" ErrorMessage="Online Application Start Date must be greater than Online Application End Date"></asp:CompareValidator>
<br />
Online Application End Date
<asp:TextBox ID="txtOnlineApplicationEndDate" runat="server" />
<asp:CompareValidator runat="server" ControlToValidate="txtOnlineApplicationEndDate"
    ControlToCompare="txtOnlineApplicationStartDate" Operator="GreaterThan" Type="Date"
    Display="Dynamic" ValidationGroup="OnlineApplicationDate" ErrorMessage="Online Application End Date must be less than Online Application Start Date"></asp:CompareValidator>
<br />
Online Application Start Date
<asp:TextBox ID="txtOnlineApplicationEditDate" runat="server" />
<asp:CompareValidator runat="server" ControlToValidate="txtOnlineApplicationEditDate"
    ControlToCompare="txtOnlineApplicationEndDate" Operator="GreaterThan" Type="Date"
    Display="Dynamic" ValidationGroup="OnlineApplicationDate" ErrorMessage="Online Application End Date must be less than Online Application End Date"></asp:CompareValidator>
<br />
<asp:Button ID="Button1" Text="Save" ValidationGroup="OnlineApplicationDate" runat="server" />