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Calling codebehind method from markup and is throwing javascript error

I have a div tag that has a click event and the method I'm trying to call is from the codebehind.
This is my div tag
<div class="DivA" runat="server" id="ThisDiv" onclick="<%ClickMe();%>"></div>
The method is a simple
public void ClickMe()
{
Response.Redirect("www.google.ca");
}
I'm just testing this before I add the real stuff to it. The error that it is throwing is...
JavaScript critical error at line 16, column 49 in http://localhost:24307/DIVPAGE.aspx
SCRIPT1002: Syntax error
this is the line that it is giving me
<div id="ThisDiv" class="DivA" onclick="<%ClickMe();%>"></div>
I have tried changing the
<%ClickMe();%>
to
<%=ClickMe()%>
But that throws the same error. Another thing I don't understand is when you look at the line with the error that it is missing the runat tag and has added other characters to the onclick event.
Thanks

You have a concept problem here, do this, and test it will work:
<asp:LinkButton id="lbClickMe" runat="server" OnClick="ClickMe">
<div class="DivA" id="ThisDiv">
The Click Me Button!
</div>
</asp:LinkButton>
That's it, when runat=server is specified ASP.NET page parser will process the element as server side, so for this elements/controls no server tags in markup are allowed except data binding tags inside control templates. So to call you method you have to put a runat server on a control that haves the Click event, this is the case of the LinkButton, inside of him you can put your div for some specific styling of your UI.
Also not that, if you really want to have the your div behaving like that, there is no problem in complicating what is simple, but in that case please do this instead:
<asp:LinkButton id="lbClickMe" runat="server" OnClick="ClickMe" Visible="False"></asp:LinkButton>
<div class="DivA" id="ThisDiv" onclick="<%= Page.GetPostBackEventReference(lbClickMe) %>"></div>
The GetPostBackEventReference extracts the javascript code necessary to simulate your link button click, but once more is preferable to use directly the link button if you can.
Hope it helps,
Regards.

The <%= %> syntax emits a string, it doesn't do anything, like a redirect.
You need to do your redirect client-side with this javascript:
window.location = 'http://my.url.com';
If you need to interact with server side code, you need to do so with AJAX communicating to a web service to get the URL you need, and then performing the redirect described above.
Update
Sorry lads, brain freeze.
Yes, indeed, you can inject a string that will be evaluated as a click handler, but the handler must be a javascript function, not a server-side one! Once the page is rendered, it can no longer interact with the server save for communicating with a web service (or if we want to get technical, web sockets as well).

You can't call server-side C# methods from the DOM like that. You can only call JavaScript functions in an HTMLElement's onclick handler.
It is correct that you can call server-side methods using the template language, however this will be executed at the time of rendering the page; you could, for example, render the results of that server-side method, but you can't use a server-side method as a handler for a client-side event. The onclick event on a DOM element can only call a JavaScript function.
ASP web controls also have an OnClick event attribute, which is probably what's confusing you; this is different from the onclick event attribute on DOM elements (ASP will create additional code for its web controls, e.g. in case of an asp:button). This works using ViewState and a postback to the server. The onclick event for a DOM element however won't do those things for you.
Adding runat="server" will convert your element to an ASP control, however it will only be an HtmlControl. In the case of a <div>, it will be an HtmlGenericControl which simply writes out the onclick attribute of your element as it is.

How can I make a RequiredFieldValidator trigger a message elsewhere on the page?

I have a page with a repeater containing RadioButtonLists which have requiredFieldValidators attached to them. I need to keep the RFV next to the control (it's the only way I can get it to work to be honest!)
However, the form is made up of a few sections contained in an accordion. This means that when the form is submitted, the item that has failed validation may not be visible, so the user won't know where the error is.
Is there a way I can also have a message by the submit button which is triggered by an RFV changing saying "please go back and check your answers" or something? I guess I'd need to use JQuery / JavaScript as it would be clientside.

There is a special ValidationSummary control for that:
<asp:ValidationSummary ID="Summary" runat="server"
DisplayMode="SingleParagraph"
HeaderText="Please go back and check your answers" />
This control is used to summarize all validation errors on the page.

Try "ValidationSummary". look for example from here.
http://www.w3schools.com/aspnet/control_validationsummary.asp

Postbackurl Vs Response.Redirect (losing data)

I have a button in my aspx page, which in code behind the value of postbackurl gets set. I updated the code to add click event handler and added Response.Redirect code to redirect user to the page once the button is clicked. The only reason i ended up adding click event was because i had to add some extra logic when the button was clicked including redirecting to same url, that was used in postbackurl. The page does get redirected on click however it seems like all the hidden fields from the field gets lost once the form get redirected to the url.
Is there anyway i can submit the form without loosing the hidden data.?

Maybe one way you can solve this problem is to use the server side Transfer() call.
http://msdn.microsoft.com/en-us/library/540y83hx(v=vs.85).aspx
In most cases I've seen what you really want to do is pass the information for the new page using URL parameters. Take all the stuff the new page needs and put it into the url (encrypt if it is security sensitive).
If the only issue you are having is when you want to stay on the same page, this is simple, just have the click event handler return without doing a response.redirect or a transfer.
Post the code if this is not working for you.

type submit vs type button

I have a button which right now is set as a type "submit". This calls the controller, execute some code and returns back to the view. When I use jquery to hide the button, I see that when I click on the button, what I have hides the button but as soon as the view is returned, the button is not hidden no more. Whereas with type "button", when I click the button, this hides the button but doesnt execute the code in the controller. Is there a way to hide the type "submit" button so when the view returns, the button is still hidden?
$('#btnAdd').click(function() {
$('#btnAdd').hide();
});

<input type='submit'> creates a button that submits a form to a server and triggers your server code. If you want the button hidden when the page comes back, you need to add logic to your page to do that. How you do this will depend on your server technology (php, .net, etc.).
The reason the behavior with <button> is different is that <button>s don't submit the form (unless you add more code to make them do that)...so the above mentioned stuff never happens. It's not so much that a <button> stays hidden as much as the page never changes/reloads. If you added code to the <button> to make it refresh the page, it'd reappear, too.

The button is shown because the page is newly displayed after submiting the form. Your "old" page, where clicked and hid the button is history.
What do you want?
Pressing a button, do something on serverside, do not change your current page:
Use a button of type button, use ajax to call the server side.
Or use a button of type submit and do what Pablo said http://en.wikipedia.org/wiki/Post/Redirect/Get on serverside.
Pressing a button, do something on serverside, give user feedback:
Use <form method="post" to markup your form. Use a submit button to call the server side. On serverside hide the submit button, if it is called by method post (calling a page with link or typing it into the address field is calling it with method = get).
What is the difference between type submit and type button?
A submit button works without javascript to send some input to serverside. The surrounding form is send to the server and the response is rendered in browser.
A button button needs a javascript onclick handler, a javascript function. The onclick handler is called when the user pressed the button.

Since the page will be reloaded upon pressing the submit button, the button will reappear. One quick and dirty to get what you want is...
First, create a hidden field
<input type="hidden" id="hidden" value="" />
Then, when you press submit, in a click event for submit button, do something like this..
$('#submit').click(function() {
$('#hiddenField').val("1");
$('#form').submit();
return false;
});
Now in your controller, use the value of hiddenField of pass some variable to the view which can be used like this...
<?php if($hidden == "1"): ?>
<input type="submit" id="submit" value="Submit" />
<?php endif; ?>
As far as the button not submitting the form is concerned, it won't submit the form, until you submit the form yourself on the click event of button. Something like this...
$('button').click(function() {
$('#form').submit();
});
Of course, as I mentioned this is a quick and dirty way to implement the function you want, there are better ways - using AJAX, also the implementation can change depending on what server side language you use (I used php over here).

When your form is submitted and your controller process the data, if certain criteria is met, you can set a temporary session variable or a cookie in server side code. So, basically the page will check for this variable on every page load. Example in PHP:
if( empty($_SESSION['temp']['hideSubmitButton']) ) {
$submitButton = '<button type="submit">Normal Button</button>';
} else {
$submitButton = '<button type="submit" disabled="disabled">Disabled Button</button>';
// or $submitButton = '';
}
But then you have to decide when to unset() the $_SESSION['temp'] or $_COOKIE['temp'] variable.

Passing master page form data to another webform

I have a master page with one form on it. It is a search form which must always be visible. When the button of that form is clicked I want the form data to be sent to search.aspx. The problem is, I don't know how. I cannot set the form action to search.aspx, because all my other pages which use the master form will go to search.aspx. This I don't want.
Hope someone can help me out :)
Thnx.

In order to pass the values of the control "txtSearch", when Server.Transfer is executed, you could do many things, including passing it via a querystring variable or setting up a session variable, and then check either of those in the Page_Load event of Search.aspx, and if it's populated, call the event that is fired when the user would hit the submit button on the Search.aspx page.
Also, if the Search.aspx file is using the same masterpage, then you can use this.Master.FindControl("txtSearch") to get the control (it you look a the source of the file after it is generated in the browser, you'll notice that controls in the master page aren't really called by their ID, rather that have something appended to them (i.e. it would now possibly be called "ctl00_txtSearch")

You could create your search form in a separate form, and get it to use GET instead of POST.
Either that, or have the master form handle the search button click and use Server.Transfer to go to the search form.

You can have multiple forms in one page I believe. So one form (your search form) would have its action set to search.aspx and the other would be set for the page itself.

ASP.NET webform pages only have one form (which would generally be included on the master page). You can set the postback url for the search button to your search page..
<asp:Button ID="btnSearch" runat="server" Text="Search" PostBackUrl="~/search.aspx" />
..or just redirect to it from the handler in your master page like this:
protected void btnSearch_Click(object sender, EventArgs e)
{
Response.Redirect(#"~/search.aspx?q=" + Server.UrlEncode(txtSearch.Text));
}
..or use Server.Transfer as suggested by David Kemp.
Note: If you use Request.Query[#"q"] on your search page to get your query, you don't need to use Server.UrlDecode() - it's done for you.

I would:
Add some code to the master page code-behind to detect the source of the POST.
Once I have the source of the POST (e.g. the Search box). I would then pass its query to the Search form.
I used a similar process with having a HTML login form on the master page.
I posted a question and subsequent solution here - check it out:
Form Elements in ASP.NET Master Pages and Content Pages
Once I got my head round it, it seemed a pretty simple and reasonably elegant solution.
The benefit of this is that you have complete control over how the data is sent to the search form. And you don't need to enable transfer of form data to the search form and all that nasty stuff, just create a new GET request to the search page and let it do what it is supposed to do :)
Hope this helps.
NOTE:
You can only have one form with runat="server" on an ASPX page. Additional forms MUST be HTML FORMS.

Because your search form is in the master page, you can probably structure it to contain 2 forms. Place the search form tags with the action set to "search.aspx" outside of the tag that is used by the rest of the site.
<body>
<form action="search.aspx>
<!--search box and submit button-->
</form>
<form runat="server">
<!--rest of page inc placeholder-->
</form>
</body>
If the structure of the page will not enable this, you can set the submit button's PosbackUrl to point to "search.aspx". In this case, "search.aspx" would need to be coded to look in the PreviousPage property for the form data, or use Request.Form to access the input.