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HTML button onserverclick event doesn't work

I'm trying to use the onclickserver on ASP.net to do something when the user clicks on a button but when I click the button nothing happens.
I really can't see what I'm doing wrong.
Here is the button:
<button id="BttnLead" class="bttnBlck" runat="server" onserverclick="BtnLead_OnClick">Lead</button>
And here the event I'm trying to use:
protected void BtnLead_OnClick(object sender, EventArgs e){}
Thank you.

I would bet it has to do with failed validation somewhere on the page, as #kman pointed out in a comment above. Are you using any <asp:FieldValidator/> controls anywhere on the page? If so, and they're not being handled correctly, all you would need to do to cause this button's postback to be triggered is to add the CausesValidation="false" property to the <button> control. This would have the button avoid the validation code that is (if it's the issue, which I really think it is) inevitably failing and thus never reaching the handler method.
P.S. It should be noted that you do NOT have to use an ASP.NET control (i.e. <asp:Button>) and the pure HTML <button> control with the runat="server" property renders a server side control just the same. However, if you're in the ASP.NET world anyway and you have access to these controls, they do provide some benefit that is nice; but that's a different conversation.

ASP.NET WebForms Confirm

I'm new to web programming with .NET.
I am developing a web page with webforms, and I want at a certain moment to programmatically show a modal window, for the user to accept or cancel, according to a question. Exactly what does the "confirm" function of JavaScript.
I tried to get it calling a JavaScript function:
Page.ClientScript.RegisterStartupScript (this.GetType (), "CallMyFunction", "MyFunction()", true);
But I need to do it without reloading the page, and I also need to control if the user has accepted or canceled and I do not know how to do it.
I've also tried getting it using the ModExPopupExtender control from DevExpress.
Can someone tell me a simple way to get what I want?
I can not understand how something so usual in web programming, and that PHP + javascript would not pose any problem can be so complicated.
All start in a one-button event on the code behind:
protected void btn1_Click(object sender, EventArgs e)
{
//I make a series of checks
//If certain conditions I want to show the confirm
//According to the user has chosen ok or cancel will perform a certain action
}
Onclientclick does not help me because before launching the "confirm" I have to do some checks on the server side.
Thank you very much.

You can use OnClientClick which is a property on most web controls.
I like to just bring up a simple confirm() dialog which executes the server code if the user clicks OK and does nothing if the user cancels the action:
<asp:Button runat="server" ID="btnSave" Click="btnSave_Click" Text="Save"
OnClientClick="return confirm('Are you sure you want to do this thing?');" />
You can do other things with it as well, but the key thing to remember is that anything you do in OnClientClick will happen before the page gets posted back to the server.
This is also perfectly valid:
<asp:Button runat="server" ID="btnSave"
OnClientClick="showModalConfirm('some message goes here');" ... />
<script>
function showModalConfirm(msg)
{
$(".modal .message").innerHtml(msg);
$(".modal").Show();
}
</script>
You can set the action that OnClientClick should perform in your codebehind in exactly the same way:
protected void Page_Load(object sender, EventArgs e)
{
btnSave.OnClientClick = "return confirm('Are you sure you want to do this thing?');";
}

You can use below code in c# to call javascript function. Below code will execute afterpostback() javascript function:
ClientScript.RegisterStartupScript(GetType(), Javascript, "javascript:afterpostback();", true);
And you can write code in javascript function to display any div or popup:
<script language="javascript" type="text/javascript">
function afterpostback() {
//Here you can write javascript to display div/modal
}
</script>

One way I've handled this previously was to have 2 buttons on the page. The first would be initially visible and labeled "Submit". The second would be initially hidden and labeled "Confirm". The "Submit" button would postback upon click and perform your server side checks/validation. If those checks failed, an appropriate error message would be displayed. If those checks passed, an appropriate "Please confirm your submission"-type message would be displayed, the "Submit" button would become hidden, and the second "Confirm" button would become visible. When that Confirm button was clicked, it would postback again and fully submit.
EDIT: I forgot to mention, there's a bit more to this that occurred to me after I initially posted. You'll have to protect the fields from being edited in the event the server-side verification is successful as you obviously don't want the user changing values and then clicking the Confirm button. That means disabling all the input controls - which could be a pain if you have a lot. You also have to give them a way to (intentionally) Edit in case the server side verification passes, you display the Confirmation, and they change their minds - so basically you'd need a third "Cancel/Edit"-type button that would put the form back in edit mode and show your initial Submit button.

Detect which button is clicked in Page_Load?

In my asp.net web page, there are a few of buttons and checkboxs. They all can cause postback.
Can I detect which control is clicked? Because I will add code for if clicked a button then do something.
I saw that some examples are done with Jquery.
Can we just do it in C#?
Thanks.

Why are you not just using the click behavior of the button:
ASPX
<asp:Button id="Button1"
Text="Click here for greeting..."
OnClick="GreetingBtn_Click"
runat="server"/>
CS
void GreetingBtn_Click(Object sender,EventArgs e)
{
}
reference here

You could check Request.Form["_EVENTTARGET"] for the control that generated the postback

well if each of the buttons submit a key value to the post or get parameters, and theyre all different it should be pretty easy! :)
localhost/home.html?button=clicked&link=selected
the above is an example of a get parameter url, you can use jquery to get those, or if its a post you would have access to them in a similar way...the previous page would have to have been a form though.

You could eventually do it by checking Request.Form["_EVENTTARGET"] but that is highly unusual and certainly not necessary.
Whatever you need to do, you can do it in the Click event handler of the given control.

You can set a server hidden control specifying the action (checkbox/textbox/button clicked) using javascript & retrieve that server control in page load to check its action & add your code for that action

ASP.NET use Hyperlinks instead of Buttons

I would like to add a Logout link to my form so our employees can log out of the job they are working on.
The code behind in my application is simple:
protected void Logout_Click(object sender, EventArgs e) {
MasterPage.Logout();
}
A asp.Button I can code by wiring up the onClick event.
How would I call this method using a asp.Hyperlink control?

You're looking for the LinkButton control. That gets rendered as an a tag, and the page will be posted back to itself so that your OnClick function can be invoked.

The Hyperlink control renders a simple hyperlink, which won't allow you to wire it up to a click handler. Try the LinkButton control instead.

Replace Hyperlink with LinkButton.
Hyperlink has no server side events.
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.linkbutton.aspx

One thing I might suggest is to simply use CSS to style your actual-fact button to adopt the look of a link, as opposed to imitating a button from something that will likely be styled differently anyway.
When imitating a button, you are relying on the user having script enabled in their browser:
The LinkButton control renders JavaScript to the client browser. The
client browser must have JavaScript enabled for this control to
function properly.
Whereas a button that is a button will submit the form.
EDIT:
As per your comment, here is a quick example you could easily adapt:
CSS:
.hyperLinkButton
{
border:none;
background:none;
color:Navy;
cursor:pointer;
}
.hyperLinkButton:hover
{
text-decoration:underline;
}
Mark-up:
<asp:Button runat="server" CssClass="hyperLinkButton"
Text="Is it a HyperLink? Is it a LinkButton? No, it's a Button!" />

ASP.NET 2.0 - Need to programmatically click a link

Is there a way to click a link programatically, so that it has the same effects as if the user clicked on it?
Example:
I have an ASP.NET LinkButton:
<asp:LinkButton id="lnkExport" runat="server" CssClass="navclass">Export</asp:LinkButton>
I have a link on a sidebar directing to the .aspx page that has this linkbutton on it. For various reasons I can't have the code for the LinkButton executed until the page has refreshed -- so I am looking for a way to force-click this LinkButton in my code once the page is completely loaded. Is there a simple/doable way to accomplish this? If it involves triggering an event, please provide a code sample if you can. Thanks.

Triggering a click event programatically on a link will trigger the “onclick” event, but not the default action(href).
And since linkbuttons come out as hrefs, so you could try doing this with Javascript.
var lnkExport = document.getElementById('<%= lnkExport.ClientID %>');
if(lnkExport){
window.location = lnkExport.href;
}

I certainly think that, there is a design and implementation flaw which forces you to conclude as you described.
Well, invoking the click event means nothing but executing the event registration method.
So, the worst suggestion I can think of is, just call the function at what point you want to happen the click event like,
lnkExport_Click(lnkExport, new EventArgs());

Rashack's post show's how to do it. You can just do it in javascript.
function ClickLink() {
document.getElementById('').click();
}
If you want this to fire after some other event, you can add code in c# to add a call to that function on the client side when the page loads.
Page.ClientScript.RegisterStartupScript(
this.getType(),
"clickLink",
"ClickLink();",
true);

I'm not sure why you'd need your page to load if you're just wanting to programmatically click that link. I'd recommend using Response.Redirect() on the server side to redirect them to that page. Not sure if there are other extenuating reasons this simple approach won't work...
--Matt

If i understand what you're saying:
<asp:LinkButton id="lnkExport" runat="server" CssClass="navclass" onclick="lnkExport_Click">Export</asp:LinkButton>
then in your codebehind or whenever call the following when you need to...
lnkExport_Click( null, null );
and make sure you've got lnkExport_Click wired up.
protected void lnkExport_Click( object sender, EventArgs e )
{
//DO Whatever here
}

<button onclick="document.getElementById('<%=this.lnkExport.ClienID%>').click()">
click me</button>