How to check multiple of TextBox value ASP.NET - asp.net

Question

This is my ASP.NET page :
<div id="dvtgl1" style="display: none">1.
<asp:TextBox ID="TxtTglCuti1" runat="server" MaxLength="1" style="width: 140px; height: 35px; padding: 12px 10px; box-sizing: border-box; border: 1px solid Silver; border-radius: 4px;" ValidationGroup="MKE"></asp:TextBox><br /><br /></div>
<div id="dvtgl2" style="display: none">2.
<asp:TextBox ID="TxtTglCuti2" runat="server" MaxLength="1" style="width: 140px; height: 35px; padding: 12px 10px; box-sizing: border-box; border: 1px solid Silver; border-radius: 4px; " ValidationGroup="MKE"></asp:TextBox><br /><br /></div>
This is my jQuery script :
$(function(){
$("#<%= TxtTglCuti1.ClientID %>").datepicker({
//dateFormat: 'dd/mm/yy',
numberOfMonths: 1,
showButtonPanel: true,
minDate: dateToday,
beforeShowDay: DisableMonday
});
$("#<%= TxtTglCuti2.ClientID %>").datepicker({
// dateFormat: 'dd/mm/yy',
numberOfMonths: 1,
showButtonPanel: true,
minDate: dateToday, beforeShowDay: DisableMonday
});
This is my VB.NET class :
If (TxtTglCuti1.Text = "") And (TxtTglCuti2.Text = "") And (TxtTglCuti3.Text = "") And (TxtTglCuti4.Text = "") And (TxtTglCuti5.Text = "") And (TxtTglCuti6.Text = "") And (TxtTglCuti7.Text = "") And (TxtTglCuti8.Text = "") And (TxtTglCuti9.Text = "") And (TxtTglCuti10.Text = "") And (TxtTglCuti11.Text = "") And (TxtTglCuti12.Text = "") Then
Response.Write("<script>alert('Data tidak boleh kosong')</script>")
Instead of building a block of code to check every TextBox that contains the date value from DateTimePicker and jQuery of all the text boxes.I built it to assign the value to an array like this :
txt_tgl_cuti(0) = TxtTglCuti1.Text
txt_tgl_cuti(1) = TxtTglCuti2.Text
The thing is, it only works for a small record.
How should I check it dynamically ? I have 12 record of text boxes and my goal is to build a function to prevent users to input duplicate date values in the TextBox

Answer 1

Below are the simle way you can check all text box values are blank,
.ASPX
<asp:PlaceHolder ID="plhDates" runat="server">
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
</asp:PlaceHolder>
<asp:Button ID="btnSubmit" Text="text" runat="server" OnClick="btnSubmit_Click" />
.VB
Protected Function MySub() As Boolean
For Each ctl As Control In plhDates.Controls
If TypeOf ctl Is TextBox Then
If (CType(ctl, TextBox).Text = "") Then
Return True
End If
End If
Next
Return False
End Function
Protected Sub btnSubmit_Click(sender As Object, e As EventArgs)
Dim isContainBlankValue As Boolean = MySub() //return true if any of the textbox have blank value
End Sub