Develop Reference

Prevent from a postback and run OnClick using jQuery

I'm trying to validate the TextBox and click the Button of asp.net.
<asp:TextBox ID="txtEmail" Placeholder="E-mail" runat="server"></asp:TextBox>
<asp:Button ID="btnLogin" OnClick="btnLogin_Click" runat="server" Text="Login" />
And here is a jQuery code which validate TextBox and then trigger the OnClick method:
var al = document.getElementById('<%=lblAlert.ClientID%>');
var email = document.getElementById('<%=txtEmail.ClientID%>');
var msg = null;
$(document).ready(function () {
$('#<%=btnLogin.ClientID%>').on('click', function (e) {
if (email.innerText == '') {
msg = 'Please! enter email address.';
al.innerText = msg;
}
else {
$('#<%=btnLogin.ClientID%>').click();
}
});
});
Edit:
OnClick method is:
protected void btnLogin_Click(object sender, EventArgs e)
{
// some code
}

You should cancel the click event, when needed, using event.preventDefault().
$(document).ready(function () {
$('#<%=btnLogin.ClientID%>').on('click', function (e) {
if (email.innerText == '') {
msg = 'Please! enter email address.';
al.innerText = msg;
e.preventDefault();
}
});
});
No need to call click again if validation succeeds.

Since in the HTML your button is already clicked when the jquery gets called, your
else {
$('#<%=btnLogin.ClientID%>').click();
}
is redundant.
Here is the thing, if you want to validate and then click, then you should use a different element as a button
If you want to use the same button (recommended) then you have to prevent the postback when the validation fails by returning false.
Simple HTML concepts
<asp:Button ID="btnLogin" OnClick="btnLogin_Click" runat="server" Text="Login" OnClientClick="return false;" />
Will never cause a postback
Here is what I would do
<asp:TextBox ID="txtEmail" Placeholder="E-mail" runat="server"></asp:TextBox>
<asp:Button ID="btnLogin" OnClick="btnLogin_Click" runat="server" Text="Login" OnClientClick="ValidateMe()" />
<script>
var al = document.getElementById('<%=lblAlert.ClientID%>');
var msg = null;
function ValidateMe() {
var email = document.getElementById('<%=txtEmail.ClientID%>');
if (email.innerText == '') {
msg = 'Please! enter email address.';
al.innerText = msg;
return false;
}
else {
return true;
}
}
</script>

Validation for my ASP textboxes is not working using javascript and ASP.NET

I just want to ask why my form validation for my asp textboxes is not working. It should be like when the user does not input a text in the textbox, a description in the paragraph tag will display to please input a text. But it is not working.Please help me on solving this.
Here is the javascript code:
function checkForm() {
var errors = [];
if ($("#itemBrand").value == "") {
errors[0] = "Please input a text!";
}
if ($("#itemModel").value == "") {
errors[1] = "Please input a text!";
}
if (errors.length > 0) {
if (errors[0] != null) {
document.getElementById("itemBrandValidate").innerHTML = errors[0];
}
if (errors[1] != null) {
document.getElementById("itemModelValidate").innerHTML = errors[1];
}
return false;
}
return true;
}
And here is the aspx:
<asp:TextBox ID="itemBrand" runat="server" BackColor="#FFFF66"
BorderColor="Black" BorderWidth="1px" Height="20px" Width="300px">
</asp:TextBox><br />
<p id="itemBrandValidate"></p>
<asp:TextBox ID="itemModel" runat="server" BackColor="#FFFF66"
BorderColor="Black" BorderWidth="1px" Height="20px" Width="300px">
</asp:TextBox><br />
<p id="itemModelValidate"></p>
<asp:Button ID="Button1" runat="server" CssClass="submitButton" Text="Save
Item" OnClick="Button1_Click" OnClientClick="return checkForm()"/>

Add ClientIdMode = "Static" on your textboxes. Otherwise the .NET platform generates an Id which is not the same as the server ID property and your Jquery selector is not working as expected.
For example:
<asp:TextBox ID="itemBrand" ClientIDMode="static" runat="server" BackColor="#FFFF66"
BorderColor="Black" BorderWidth="1px" Height="20px" Width="300px">
</asp:TextBox>

Client side id of asp.net server controls is different from server side id.
You may use ClientIDMode = "Static" (introduced in .NET 4.0) or you might use ClientID as shown below , also I've tried to re-write your validation function a bit.
function checkForm() {
var success = true;
var itemBrandID = "<%= itemBrand.ClientID %>" ;
if ($("#" + itemBrandID).value == "") {
success = false;
document.getElementById("<%= itemBrandValidate.ClientID %>").innerHTML = "Please input a text!";
}
var itemModelID = "<%= itemModel.ClientID %>" ;
if ($("#" + itemModelID).value == "") {
success = false;
document.getElementById("<%= itemModelValidate.ClientID %>").innerHTML = "Please input a text!";
}
return success;
}
Also suggest you to read this excellent post by Rick Strahl on A generic way to find ASP.NET ClientIDs with jQuery
Hope this helps !

Disabling RequiredFieldValidator for hidden fields

I have a dropdownlist that should be mandatory when not hidden, so i have a RequiredFieldValidator for this.
<table runat="server" id="tblLocations" class="ts1">
<tr>
<td class="tr0">
Location:
</td>
<td>
<asp:DropDownList ID="ddlLocations" runat="server">
</asp:DropDownList>
<asp:RequiredFieldValidator ID="rfvDdlLocations" runat="server" ControlToValidate="ddlLocations" InitialValue="0" validationgroup="LocationValidation" ErrorMessage="Please select a Location" />
</td>
</tr>
</table>
When a radio button is selected I set the visibility of this table to false.
I want to disable validation of this field when not visible so I set this on the radio button changed event:
rfvDdlLocations.Enabled = tblLocations.Visible;
This doesn't disable the verification however.
I have tried using JQuery as suggested elsewhere but this has no effect either:
<script type="text/javascript">
$("[id$='btnDelegate']").click(function () {
if (!$("[id$='tblLocations']").is(':visible')) {
ValidatorEnable($("[id$='rfvDdlLocations']")[0], false);
}
//ValidationSummaryOnSubmit("LoginUserValidationGroup");
if (Page_ClientValidate("LocationValidation")) {
alert('it is valid');
return true;
}
else {
alert('Not valid');
return false;
}
});

you should use a customvalidator in this case as below
<asp:CustomValidator ID="cvDdlLocations" runat="server" ControlToValidate="ddlLocations" ValidationGroup="LocationValidation" ErrorMessage="Please select a Location" OnServerValidate="cvDdlLocations_ServerValidate" ClientValidationFunction="validateLocation" />
and for client validation
function validateLocation(s, args) {
if($('#'<%= Radio.ClientID %>).is(':checked')){
args.IsValid = true;
}
else {
args.IsValid = $('#<%= ddlLocations.ClientID%>').val() != "0";
}
}
and for server validation
protected void cvPrice2Edit_ServerValidate(object source, ServerValidateEventArgs args)
{
args.IsValid = true;
if(!Radio.Checked) {
args.IsValid = ddlLocations.SelectedValue != "0";
}
}
I hope this helps

Cancel ajax modalpopupextender using javascript

I have a modalpopupextender with a targetcontrolid = buttCopyFormula. The buttCopyFormula is wrapped in a span tag for the user to verify they want to proceed. The button also has a javascript function that verifies there is text in one of the fields and if there is places it in a textbox within the modalpopup.
If there isn't text in the field I want to cancel the popup and display a message.
I've had the span around the button for a while, but am just adding the verification function. I would imagine there is a better way to do this, but just not sure what it is.
What is the best way to execute this functionality?
TargetControl Button
<span onclick="return confirm('Copy the selected formula?')">
<asp:ImageButton ID="buttCopyFormula" ImageAlign="AbsBottom" OnClientClick="transferName()" runat="server" ImageUrl="~/images2020/copy_32.png" />
<b style="color:White">Copy</b>
</span>
Modal Popup
<asp:ModalPopupExtender ID="ModalPopupExtender2" Y="20" runat="server"
BackgroundCssClass="modalBackground" CancelControlID="buttFormulaCancel"
PopupControlID="Panel2" TargetControlID="buttCopyFormula">
</asp:ModalPopupExtender>
<asp:Panel ID="Panel2" runat="server" CssClass="modalQuestionBackground"
Style="display:none"><br />
<h5>Enter a Name for the Formula</h5>
<br /><br />
Formula Name:
<asp:TextBox ID="txtFormulaNameNew" CssClass="controltext" Width="65%" runat="server" Text=""></asp:TextBox><br /><br />
<center>
<asp:Button ID="buttFormulaSaveNew" runat="server" CssClass="button"
OnClick="buttFormulaSaveNew_Click" Text="Save Formula" />
<asp:Button ID="buttFormulaCancel" runat="server" CssClass="button"
Text="Cancel" />
</center>
<br />
</asp:Panel>
JavaScript Function
function transferName() {
var v = document.getElementById("ctl00_ContentPlaceHolder1_txtFormulaNameNew").value;
var f = document.getElementById("ctl00_ContentPlaceHolder1_txtFormulaName");
if (v === "") {
alert("Please select the formula you want to copy before proceeding");
return false;
}
f.value = v
}
I've been working on this and first removed the span around the button, put a fake hyperlink for the modal popup and added a behavior id to the popup. I have also changed the javascript as follows...
New Javascript
function transferName() {
var v = document.getElementById("ctl00_ContentPlaceHolder1_txtFormulaNameNew").value;
var f = document.getElementById("ctl00_ContentPlaceHolder1_txtFormulaName");
if (f === "") {
alert("Please select the formula you want to copy before proceeding");
return false;
} else {
if (confirm('Copy selected formula?')) {
f.value = v;
var mod = $find("ModalPopupExtender2");
alert(mod.id.toString);
mod.show;
return false;}
}
}
I still can't get the modalpopup to show. I imagine it's because it's wrapped in an update panel. Any ideas??

You may subscribe to showing event of ModelPopupExtender and cancel showing dependent on some conditions. Put script below at page AFTER THE ScriptManager control
Sys.WebForms.PageRequestManager.getInstance().add_pageLoaded(pageLoadedHandler);
function pageLoadedHandler(sender, args){
var popupExtender = $find("ModalPopupExtender2"); // BehaviorId of popup extender
popupExtender.remove_showing(onPopupShowing);
popupExtender.add_showing(onPopupShowing);
}
function onPopupShowing(sender, args) {
var txtFormulaNameNew;
var txtFormulaName = $get("<%= txtFormulaName.ClientID %>");
if (formulaTextBox.value.length === 0) {
alert("Please select the formula you want to copy before proceeding");
args.set_cancel(true);
} else {
if (confirm('Copy selected formula?')) {
txtFormulaNameNew = $get("<%= txtFormulaNameNew.ClientID %>");
txtFormulaNameNew.value = txtFormulaName.value;
}
}
}

Validating Textbox with CustomValidator's ClientValidationFunction not firing

I am having some serious issues with this. I have a two fields like this, both of them being assigned datepickers with jquery.
<asp:TextBox ID="RTRP" runat="server" CssClass="textEntry" Width="120"></asp:TextBox>
<asp:CustomValidator runat="server" ID="CustomValidator3"
ControlToValidate="RTRP"
Text="No date selected"
ValidateEmptyText="True"
ClientValidationFunction="clientValidate"
Display="Static">
</asp:CustomValidator>
<asp:TextBox ID="ContEd" runat="server" CssClass="textEntry" Width="120"></asp:TextBox>
<asp:CustomValidator runat="server" ID="CustomValidator1"
ControlToValidate="ContEd"
Text="No date selected"
ValidateEmptyText="True"
ClientValidationFunction="clientValidate"
Display="Static">
</asp:CustomValidator>
With the following javascript to validate it.
$("#<%=RTRP.ClientID %>").datepicker();
$("#<%=ContEd.ClientID %>").datepicker();
function clientValidate(sender, args) {
args.IsValid = args.Value.length > 0;
}
Both get their datepickers, but the validation function simply refuses to be fired and always allows the form to submit. I am completely lost here, what am I doing wrong?

You are checking if a string's length is less than 0 (what is never true) here:
function clientValidate(sender, args) {
if (args.Value.length < 0) {
args.IsValid = false;
} else {
args.IsValid = true;
}
}
I'm not sure if this is what you want(you could simpy use a RequiredFieldValidator), but...
function clientValidate(sender, args) {
args.IsValid = args.Value.length > 0;
}

If you assign $.datepicker() behaviour to any text, and run page.. you will find that textbox on which you override jQuery datepicker had css set display : none.. so that might be the reason that custom validation not getting for that textbox...

why dont you use
<asp:RequiredFieldValidator id="id" controltovalidate="controlname" erormessage="please enter the dates">
</asp:RequiredFieldValidator>
correct me i am wrong

Change you method to this.and try again
function clientValidate(sender, args)
{
if(Page_ClientValidate())
{
if (args.Value.length < 0)
{
args.IsValid = false;
} else
{
args.IsValid = true;
}
}
}