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Javascript confirm dialog coming up twice; Jumping back after clicking Element

Beginner here, so please be gentle.
I'm trying to ask the User for confirmation. When he accepts, my javascript invokes a Button to run some code behind. The code behind will run a JavaScript function which alerts, just so I can see if it all works. What happens is, that after my first confirm() dialog, a second dialog appears. After confirming again, the code runs and my second JavaScript function confirms by alerting. But after I press okay on that, the whole thing jumps back to my first function and I get into a loop!
ASPX:
<script type = "text/javascript">
function ConfirmComputerOverwrite(ComputerName) {
if (confirm("Overwrite present computer " + ComputerName + " ?"))
{
}
else
{
}
document.getElementById("Test").click()
}
function allworkedout()
{
alert("asdf");
}
Code behind:
public string ComputerName = "";
protected void Page_Load(object sender, EventArgs e)
{
string ComputerName = "Computer1";
this.ComputerName = ComputerName;
StringBuilder sb = new StringBuilder();
sb.Append("ConfirmComputerOverwrite('" + ComputerName + "');");
ScriptManager.RegisterStartupScript(this, GetType(), "ConfirmComputerOverwrite", sb.ToString(), true);
}
protected void Test_Click(object sender, EventArgs e)
{
StringBuilder sb = new StringBuilder();
sb.Append("allworkedout();");
ScriptManager.RegisterStartupScript(this, GetType(), "allworkedoutID", sb.ToString(), true);
}
Thanks in advance !

Unless you are using ajax, the whole page is reloaded after click, so your javascript is executed again, prompting for confirmation, etc...

server side alert message that shows unwanted when get back and reload the page

I have a submit button and below is the code in the onClick event :
protected void btnSubmit_Click(object sender, EventArgs e)
{
...
ScriptManager.RegisterClientScriptBlock(this, GetType(), "alertMessage", "alert('Submitted')", true);
}
This code works.
But the problem is when user go to next page by this:
Response.Redirect("page2.aspx");
and when click backspace to get back to page1 and,
before the reload,
the following message box appears!!
this problem happened again when we refresh(F5) the page1 after submiting
how will I solve this?
I tried:
1. if(isPostback)// before the alert
2. string message = "Submitted";
System.Text.StringBuilder sb = new System.Text.StringBuilder();
sb.Append("<script type = 'text/javascript'>");
sb.Append("window.onload=function(){");
sb.Append("alert('");
sb.Append(message);
sb.Append("')};");
sb.Append("</script>");
ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", sb.ToString());

In such case, you can implement a special code block to detect browser refresh as
private bool refreshState;
private bool isRefresh;
protected override void LoadViewState(object savedState)
{
object[] AllStates = (object[])savedState;
base.LoadViewState(AllStates[0]);
refreshState = bool.Parse(AllStates[1].ToString());
if (Session["ISREFRESH"] != null && Session["ISREFRESH"] != "")
isRefresh = (refreshState == (bool)Session["ISREFRESH"]);
}
protected override object SaveViewState()
{
Session["ISREFRESH"] = refreshState;
object[] AllStates = new object[3];
AllStates[0] = base.SaveViewState();
AllStates[1] = !(refreshState);
return AllStates;
}
In the button submit you can do it as
protected void btn3_Click(object sender, EventArgs e)
{
if (isRefresh == false)
{
Insert Code here
}
}

on buttonclick check if file exist then prompt message and revert

I have a scenario where I want to check if user adds data with same date and same region again, it should give him a prompt alert.
I tried this with code behind,like below:-
protected void btnSave_Click(object sender, EventArgs e)
{
DataTable dtExcel = new DataTable();
dtExcel.Clear();
string StrCount = String.Empty;
string connString = "";
HttpPostedFile File = FileUpload1.PostedFile;
string strFileType = Path.GetExtension(FileUpload1.FileName).ToLower();
string path = FileUpload1.PostedFile.FileName;
string Filename = path.Substring(path.LastIndexOf("\\") + 1, path.Length - path.LastIndexOf("\\") - 1);
path = Server.MapPath(#"~/Excels/" + "/" + Filename.ToString());
File.SaveAs(path);
if (strFileType.Trim() == ".xls")
{
connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
}
else if (strFileType.Trim() == ".xlsx")
{
connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
}
string query = "SELECT * FROM [Sheet 1$]";
OleDbConnection conn = new OleDbConnection(connString);
conn.Close();
if (conn.State == ConnectionState.Closed)
conn.Open();
OleDbCommand cmd = new OleDbCommand(query, conn);
OleDbDataAdapter daExcel = new OleDbDataAdapter(cmd);
daExcel.Fill(dtExcel);
conn.Close();
DataTable DtMain = CF.ExecuteDT("select Tran_type, Order_Date, Region_Mkey from WMS_Future_Del_Order_Hdr where Tran_type = '" + CmbTypeOfAsn.SelectedValue + "' and Order_Date = convert(datetime,'" + TxtEdate.Value + "',103) and Region_Mkey = '" + ddlRegion.SelectedValue + "'"); // checks the duplicate records here
if (DtMain.Rows.Count > 0)
{
ClientScript.RegisterStartupScript(this.GetType(), "SuccessScript", "myTestFunction()", true);
}
Also see my function for prompting the alert for duplicate message
function myTestFunction() {
if (confirm('Are you sure you want to override the file ?')) {
return true;
}
else {
return false;
}
}
but what happens here is even after cancel click, the excel file is uploaded and gets saved. I dont know why

Although Abbas Kapasi's solution based on AJAX is good one (and you do not want to/can not use the solution based on CheckBox as I suggested in my other post codebhind-javascript-alert-for-yes-and-no-not-working-exactly), if you are not familiar with AJAX or don't want to use AJAX then you may achieve it using following approach. It may seem a bit odd but you may modify it according to your requirements:
I am splitting the code to upload and find existing file/record in one procedure and the code to write/overwrite the records in another sub-procedure.
Then I am using two LinkButtons, LinkButtonLoad and LinkButtonOverwrite.
LinkButtonLoad will be attached to the call the main procedure which uploads and finds existing file/record. LinkButtonOverwrite will call the procedure to write/overwrite the records. LinkButtonOverwrite will remain hidden from the user.
In the first procedure if the system finds existing file/record it will show a client side prompt to the user to overwrite or not. If the file/record does not exist it will call second sub-procedure to write the records.
On client side, if the prompt is displayed for existing file/record and the user selects Cancel/No the process will not proceed. If the user selects OK/Yes then I'll be calling the procedure linked to the LinkButton2 to overwrite the records.
Now putting it all together:
In aspx/front end
<asp:LinkButton ID="LinkButtonLoad" runat="server" Text="Load Records" CssClass="button" ... />
<asp:LinkButton ID="LinkButtonOverwrite" runat="server" Text="ow" CssClass="button hidden" ... />
I'm using hidden CSS class to hide the button .hidden {display: none;}. Do NOT use visible="false" attribute, it'll not be available on the client side.
JavaScript on client side:
function myTestFunction() {
if (confirm('Are you sure you want to override the file ?')) {
// get the action attribute of the hidden LinkButtonOverwrite here and call it on OK
// as an alternative you may also invoke the click event of this button
var defaultAction = $('#<%=LinkButtonOverwrite.ClientID %>').prop("href");
window.location.href = defaultAction;
}
else {
return false;
}
}
LinkButtonLoad in code behind:
protected void LinkButtonLoad_Click(object sender, EventArgs e)
{
//==============================================================
// YOUR CODE TO UPLOAD THE FILE, SAVE IT SO WE MAY USE IT AGAIN
//==============================================================
if (DtMain.Rows.Count > 0)
{
ClientScript.RegisterStartupScript(this.GetType(), "SuccessScript", "myTestFunction()", true);
}
else
{
MySubToOverwrite();
}
}
LinkButtonOverwrite in code behind:
protected void LinkButtonOverwrite_Click(object sender, EventArgs e)
{
//===========================================================
// AS THE FILE IS ALREADY UPLOADED IN LINKBUTTONUPLOAD_CLICK
// YOU MAY ACCESS IT AND PERFORM REQUIRED OPERATIONS
//===========================================================
MySubToOverwrite();
}
MySubToOverwrite() code in behind:
private void MySubToOverwrite()
{
//==========================================================
// OVERWRITE YOUR RECORDS HERE
// FROM THE FILE ALREADY UPLOADED IN LINKBUTTONUPLOAD_CLICK
//==========================================================
}

Detecting duplicate records
There are a few ways you can do this. Just going to touch on the big picture here, in order of my personal preference:
Easiest method: Don't check. Prompt first. Provide a checkbox up front.
Use 2 Ajax requests: one to check for existing record, and another to save the file (if user said "OK" or if file not yet exists). Challenge: multiuser environments.
Multi-step POST back. Server code injects a dynamic control (or shows a hidden static one) that prompts user to overwrite. Ugly, but does not require JS. You may remember this from the '90s.
Versioning: more advanced, more complex, but for Enterprise systems this is the way to go. Do not overwrite files with same identifier; store a different version of it. Then you get a nice history and audit trail of who changed it. Makes it easy to go back to fix mistakes, blame people, etc.
Canceling the PostBack (if using option 3 or other postback method)
You need to bind to the correct button, and to prevent POST to the server (AKA "postback") you must return false in either
the click event handler of the rendered input type="button"
or
the submit event handler if the form
You can accomplish this by embedding the return value to myTestFunction() in the asp:Button itself:
<asp:Button ID="btnSave" runat="server" Text="Save"
OnClientClick="if(!myTestFunction()){return false;}"
OnClick="btnSave_Click" />
<script>
function myTestFunction() {
return confirm('Override the file?');
}
</script>

use ajax function with webservice to check the same data and region
Submit button code
<asp:Button ID="btnupload" runat="server" OnClientClick="javascript return checkData()"
Text="Upload" OnClick="btnupload_Click"></asp:Button>
Javacript
<script>
function checkData() {
$.ajax({
type: "POST",
url: "demo.aspx/functionName1",
data: "{parameter1:'" + param1 "',parameter2:'" + param2 + "'}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (msg) {
if(msg.d == 'Yes'){
if (confirm('Are you sure you want to override the file ?')) {
return true;
}
else {
return false;
}
}
else{
return true;
}
}
});
}
</script>
C# Code
using System.Web.Services; --- use this class
[WebMethod]
public static string functionName1(string parameter1, string parameter2)
{
------------------------------;
if(check Condition)
return "Yes";
else
return "No"
}

In reality, you just need the following to make it work. Use RegisterOnSubmitStatement instead of RegisterStartupScript. It would let you add script that executes in response to the button's onclick event. The script is executed before the button event is invoked, and gives you an opportunity to cancel the event.
Code-behind:
protected void Page_Load(object sender, EventArgs e)
{
// You can place this in any method where you want to do the validation.
String scriptText =
"return confirm('Are you sure you want to override the file ?')";
ClientScript.RegisterOnSubmitStatement(this.GetType(),
"ConfirmSubmit", scriptText);
}
protected void btnSave_Click(object sender, EventArgs e)
{
}
Markup :
<asp:Button id="ConfirmSubmit" runat="server" OnClick="btnSave_Click"/>

Javascript to pass value from server to client doesnt work

I have a fileupload control and a button in a webform.When i click on the button after selecting fileupload,it should save the image and rename it with a GUID.
protected void btnUpload_Click(object sender, EventArgs e)
{
string fileName = string.Empty;
string filePath = string.Empty;
string extension = string.Empty;
try
{
//Check if Fileupload control has file in it
if (FileUpload1.HasFile)
{
// Get selected image extension
extension = Path.GetExtension(FileUpload1.FileName).ToLower();
//Check image is of valid type or not
if (extension == ".jpg" || extension == ".jpeg" || extension == ".png" || extension == ".gif" || extension == ".bmp")
{
//Cretae unique name for the file
fileName = Guid.NewGuid().ToString() + extension;
//Create path for the image to store
HiddenField1.Value = fileName;
filePath = Path.Combine(Server.MapPath("~/Images"), fileName);
//Save image in folder
FileUpload1.SaveAs(filePath);
//Show the panel and load the uploaded image in image control.
//pnlCrop.Visible = true;
}
The above code works just fine,saves the image and passes the GUID to the hiddenfield.Now i want to pass the value of hiddenfield to a client side variable and then display it as an alert.
<script type="text/javascript">
function showfilename() {
setTimeout(function () {
var dpGUID = document.getElementById('<%= HiddenField1.ClientID %>').value;
alert(dpGUID);
},3000)
}
</script>
Reason for using timeout? Because i want to read value of hiddenfield after it has been assigned the value on button click.
Note:I am using two functions on Buttonclick.One on client side and other on server side as follows :
<asp:Button ID="btnUpload" runat="server" OnClick="btnUpload_Click" Text="Button" OnClientClick="showfilename()" />
Is it possible? If yes,what could be causing a problem?

Try using a RegisterClientScriptBlock
protected void btnUpload_Click(object sender, EventArgs e)
{
/*All your code here*/
//instead of HiddenField1.Value = fileName; write the line below
ScriptManager.RegisterClientScriptBlock(this, typeof(Page), "callJsFunction", "alert('" + fileName + "');", true);
}
and now you can get rid of the OnClientClick="showfilename() and the HiddenField

How to get the confirm() value with C# code

I have a button which needs get the confirm() value to do the database operation. For example: when clicking the button, a message popup to confirm "yes or no", if yes, it will do the deletion operation in database, if no, it will clear the textbox. How can I get the returned value from Javascript confirm() function. Please advise.
string jScript;
jScript = "<script> function processConfirm(answer) {if (answer) {return 'Facilitator Deleted';}else {return 'Cancelled';}} var confirmAnswer = confirm('You sure to delete ?');var theAnswer = processConfirm(confirmAnswer);alert(theAnswer);</script>";
ClientScript.RegisterClientScriptBlock(this.GetType(), "keyClientBlock", jScript);
/* SqlCommand cmd = new SqlCommand("TrainerFilter", conn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add("#EmployeeID", SqlDbType.Int, 50).Value = TextBox1.Text.Trim();
cmd.Parameters.Add("#result", SqlDbType.Int, 50).Direction = ParameterDirection.Output;
conn.Open();
cmd.ExecuteNonQuery();*/

You can store the value of confirm_proceed() in an asp:HiddenField
You can modify your script as follows:
function confirm_proceed()
{
var hiddenField = document.getElementById('hiddenFieldId');
if (confirm("Are you sure you want to proceed?")==true)
{
hiddenField.value = 'true';
return true;
}
else
{
hiddenField.value = 'false';
return false;
}
}

This is a bit confusing, but assuming this confirm is tied to a button click, you would usually do something like this:
<script type="text/javascript">
processConfirm = function() {
var result = confirm("Are you sure you want to delete this?");
if (!result) {
alert("Cancelled"); //or set a label or whatever
return false; //cancel postback
}
return true; //perform postback
}
</script>
<asp:Button ID="Button1" runat="server" OnClientClick="return processConfirm();" OnClick="Button1_Click" />
And in the code-behind:
protected void Button1_Click(object sender, EventArgs e)
{
//perform the delete logic since because if you reach here
//you know that the user confirmed
//throw up an alert when the page is reloaded confirming that the deletion
//you could also set a label here instead of an alert if you wanted
Page.ClientScript.RegisterStartupScript(this.GetType(), "confirmDelete", "alert('User was deleted');", true);
}