Countdown timer avoiding postback ASP.NET VB

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Can anyone let me know what is wrong with this code? I switched it from C# to vb and it works without any mistakes in c# i want to place timer in web form and not reset with postback or click button

default.aspx

ASP.NET

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <style type="text/css">
#CountDownPanel {color: blue; background-color: yellow; font-size: 18px;}
    </style>
    <asp:Label ID="Label1" runat="server" Text="Time Remaining:"></asp:Label>&nbsp;
        <span id="CountDownPanel" runat="server"></span>
        <asp:HiddenField ID="TotalSeconds" runat="server" Value="2700" />
    </div>
    </form>
</body>
</html>

default.aspx.vb

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Public Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
        If Not IsPostBack Then
            NoCache(HttpContext.Current)
        End If

    End Sub

    Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As EventArgs)
        If Page.IsPostBack Then
            Dim ticks As Long = Convert.ToInt64(Me.StartTicks)
            Dim startTime As DateTime = New DateTime(ticks)
            Dim elapsed As TimeSpan = (startTime.AddMinutes(180) - DateTime.Now)
            Me.TotalSeconds.Value = Convert.ToInt32(elapsed.TotalSeconds).ToString()
        End If

        ClientScript.RegisterClientScriptInclude("script", "CountDown.js")
    End Sub

    Private ReadOnly Property StartTicks As String
        Get
            Dim startTicksString As String = CType(Session("StartTicks"), String)
            If String.IsNullOrEmpty(startTicksString) Then
                startTicksString = DateTime.Now.Ticks.ToString()
                Session("StartTicks") = startTicksString
            End If

            Return startTicksString
        End Get
    End Property

    Private Sub NoCache(ByVal context As HttpContext)
        context.Response.AddHeader("Pragma", "no-cache")
        context.Response.CacheControl = "no-cache"
        context.Response.Cache.SetAllowResponseInBrowserHistory(False)
        context.Response.Cache.SetCacheability(HttpCacheability.NoCache)
        context.Response.Cache.SetNoStore()
        context.Response.Expires = -1
    End Sub
End Class

countdown.js

var _countDowncontainer = 0;
var _currentSeconds = 0;

function ActivateCountDown(strContainerID, initialValue) {
    _countDowncontainer = document.getElementById(strContainerID);

    if (!_countDowncontainer) {
        alert("count down error: container does not exist: " + strContainerID +
			"\nmake sure html element with this ID exists");
        return;
    }

    SetCountdownText(initialValue);
    window.setTimeout("CountDownTick()", 1000);
}

function CountDownTick() {
    if (_currentSeconds <= 0) {
        alert("your time has expired!");
        //document.getElementById("ctl01").disabled = true;
        document.getElementById("ctl01").click();
        return;
    }

    SetCountdownText(_currentSeconds - 1);
    window.setTimeout("CountDownTick()", 1000);
}

function SetCountdownText(seconds) {
    //store:
    _currentSeconds = seconds;

    //get minutes:
    var minutes = parseInt(seconds / 60);

    //shrink:
    seconds = (seconds % 60);

    //get hours:
    var hours = parseInt(minutes / 60);

    //shrink:
    minutes = (minutes % 60);

    //build text:
    var strText = AddZero(hours) + ":" + AddZero(minutes) + ":" + AddZero(seconds);

    //apply:
    _countDowncontainer.innerHTML = strText;
}

function AddZero(num) {
    return ((num >= 0) && (num < 10)) ? "0" + num : num + "";
}
window.onload = WindowLoad;

function WindowLoad(event) {
    ActivateCountDown("CountDownPanel", document.getElementById("TotalSeconds").value);
}

What I have tried:

I TRY THIS CODE with VB.NET but NOT WORKING. I CONVERTed IT FROM C#. It works WITH C#

Posted 13-May-17 21:35pm

ahmed_hashem

Updated 14-May-17 14:16pm

Bryian Tan

v2

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Bryian Tan · Accepted Answer · 2017-05-14T14:16:00

You didn't indicate what not working in the post. Look like the Page_PreRender did not get trigger. Couple of thing you do. I think #1 should do the trick based on your scenario.

1. Change the AutoEventWireup="false" to AutoEventWireup="true"

2. Leave the AutoEventWireup="false" and change the method

VB

Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As EventArgs)
End Sub

TO

VB

Protected Overrides Sub OnPreRender(e As EventArgs)
        MyBase.OnPreRender(e)
 End Sub

asp.net - OnPreRender vs Page_PreRender - Stack Overflow[^]