TextChanged event not firing for text box, when the text is changed from javascript

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C#

ASP.NET

I have a text box which i m filling of date from the calendar extendar and the code is as below:-

<label for="input-one" class="float">Date</label><br />                  
                        <asp:TextBox ID="txtDate" runat="server" CssClass="inp-text" Enabled="false" AutoPostBack="true"
                            Width="300px" ontextchanged="txtDate_TextChanged"></asp:TextBox>
                            <asp:ImageButton ID="btnDate2" runat="server" AlternateText="cal2" 
                            ImageUrl="~/App_Themes/Images/icon_calendar.jpg" style="margin-top:auto;" 
                                CausesValidation="false" onclick="btnDate2_Click" />
                        <ajaxToolkit:CalendarExtender ID="calExtender2"  runat="server" 
                            Format="dddd, MMMM dd, yyyy" OnClientDateSelectionChanged="CheckDateEalier" 
                            PopupButtonID="btnDate2" TargetControlID="txtDate" />
                        <asp:RequiredFieldValidator ID="RequiredFieldValidator7" runat="server" 
                            ControlToValidate="txtDate" ErrorMessage="Select a Date" Font-Bold="True" 
                            Font-Size="X-Small" ForeColor="Red"></asp:RequiredFieldValidator><br />

javascript code is :-

function CheckDateEalier(sender, args) 
{
    sender._textbox.set_Value(sender._selectedDate.format(sender._format))

}

My requirement is that as the date is entered in to the textbox , i want to call the below method.

public void TimeSpentDisplay()
    {
        string date = txtDate.Text.ToString();
        DateTime dateparsed = DateTime.ParseExact(date, "dddd, MMMM dd, yyyy", null);
        DateTime currentDate = System.DateTime.Now;
        if (dateparsed.Date > currentDate.Date)
        {
            divtimeSpent.Visible = true;
        }
        if (dateparsed.Date < currentDate.Date)
        {
            divtimeSpent.Visible = true;
        }
        if (dateparsed.Date == currentDate.Date)
        {
            divtimeSpent.Visible = false;
        }
    }

Please help me that how i achieve this as i m calling this method inside txtDate_TextChanged method but the event is not firing as the text is changed inside the textbox. Please suggest me that how i achieve this or give me an alternate idea to fulfill my requirement.