How can I write JavaScript code in asp.net in code behind using C#?
For example:
I have click button event when I click the button I want to invoke this java script code:
alert("You pressed Me!");
I want to know how to use java script from code behind.
Actually, this is what you need:
string myScriptValue = "function callMe() {alert('You pressed Me!'); }";
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "myScriptName", myScriptValue, true);
Copy all of javascript into string and then register it into your aspx page in code-behind. Then in aspx page, you can call the javascript function whenever you want. You should write this code in Page_Load method in C# page.
Have a look at the ScriptManager class' RegisterClientScriptBlock and RegisterStartupScript methods.
One way to put some javascript onto the page into a specific location do this:
ASP.Net
<script type="text/javascript">
<asp:Literal id="litScript" runat="server" />
</script>
C#
litScript.Text = "alert("Hello!");"
Of course, you can put anything in there, and I'd recommend a javascript library.
Using the Scriptmanager is also an option.
Not an answer, but a suggestion.
Mixing your js within your code-behind can come back to haunt you, I agree with Adrian Magdas.
Anytime you need to make a simple change/update to your javascript you'll have to re-build your project, which means re-deploying instead of simply pushing out a single .js file.
Something like:
btnSomething.ClientClick = "alert('You pressed me!');";
You might also want to read up on the ScriptManager control and outputting blocks of script.
The right answers usually is "You don't". It's better to define your code in a .js file and use jQuery to hook-up the desired events.
$(document).ready(function() {
$('#myBtn').click(function() {
alert('Handler for .click() called.');
});};
If you want to register a script that will be used in connection with an UpdatePanel (AJAX) use ScriptManager class as Sani Huttunen pointed.
Otherwise you should use the class ClientScriptManager (methods Page.ClientScript.RegisterClientScriptBlock or Page.ClientScript.RegisterStartupScript)
As other user pointed, normally registering a script on the code behind can and should be avoided. It's not a very nice practice and you should do it only in cases where you have no other option.
Response.Write("<script language='javascript'>alert('You pressed Me!');</script>");
Related
When a user clicks a button on ASP.net page, I need to
Save file from asp:fileUpload in a folder on a server - I guess this needs to be done in C#, like in How to correctly use the ASP.NET FileUpload control
Run a javascript function like in How to call javascript function from asp.net button click event
Is there a way to combine C# and Javascript to achieve what I need? If not, how should I do it?
Try using the onClientClick property of the asp:button element.
Ex, on your .aspx file:
<script type="text/javascript">
function myFunction()
{
alert('hi');
}
</script>
...
<asp:button id="Button1"
usesubmitbehavior="true"
text="Open Web site"
onclientclick="myFunction()"
runat="server" onclick="Button1_Click" />
And in your code behind (.aspx.cs)
void Button1_Click (object sender, EventArgs e)
{
if (this.FileUpload1.HasFile)
{
this.FileUpload1.SaveAs("c:\\" + this.FileUpload1.FileName);
}
}
More info at
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclientclick.aspx
Note that no JavaScript actually "runs" until the server-side code (C# in this case) has entirely completed and the resulting page is returned to the client. Once that page renders on the client, then JavaScript runs on the client.
So in order to execute your JavaScript code, all you need to do is include it in the page being returned to the client. There are a number of ways to do this, and the options depend on whether you're using WebForms or MVC.
You might use something like RegisterStartupScript in WebForms, for example. Or, you could just have the JavaScript code exist in a PlaceHolder control with Visible=false and only make the control visible in the response which intends the JavaScript code to run. (Roughly the same method is also easily usable in MVC by just wrapping the JavaScript code in a server-side condition to determine whether to render it or not.)
The main thing to remember is that you're not "running the JavaScript code from C#" or anything like that. There's a hard separation between server-side and client-side code. The server-side code ultimately builds the page that it sends back to the client, and that page can include JavaScript code to run on that client.
I have an ascx control that is loaded in an aspx page.
How can I instruct my ascx to run javascript once it is rendered in the browser.
It should run on every postback as well.
I looked around but could not find a satisfactory answer.
Have you tried using the "RegisterStartupScript" method along with JQuery to call a JS function?
This code might help you:
ScriptManager.RegisterStartupScript(Page, GetType(Page), "myScript", "$(function() {{ alert ('Your page is loaded.'); }});", True)
You can replace the alert with any JS function you want :)
I hope this helps.
I have default.aspx with a "Submit" Button and a code behind function called as "btn_Submit" which will perform submit action. Once I deploy the application and if there is any logical problem in btn_Submit code, then I can use runat=server script in default.aspx file and I need not go for another deployment.
But When I tried the same for ascx file, it works very well in development environment i.e in VS but when I move the same to Test server, system throws function not defined. I have renamed the existing function name.
So is it possible to add runat=server script and add c# code in ascx file?
Yes it is possible..
You have to surround your code with markup
<script language="c#" runat="server">
public void Page_Load(object sender, EventArgs e)
{
//hello, world!
}
</script>
Take a look to thisquestion! I think it will help you..
But it is really better to separate your code..
Did you tell the button which method to run on submit? With "auto event wireup" it will try to find a "buttonname_Click" method if you didn't specify anything. If that doesn't exist, you will get an error.
To call a method with a different name, specify that in the OnClick property of the button.
I am not sure why this happened and still was not able to solve it, So redeployed the application :(
How can I detect server-side (c#, asp.net mvc) if the loaded page is within a iframe? Thanks
This is not possible, however.
<iframe src="mypage?iframe=yes"></iframe>
and then check serverside if the querystring contains iframe=yes
or with the Referer header send by the browser.
Use the following Code inside the form:
<asp:HiddenField ID="hfIsInIframe" runat="server" />
<script type="text/javascript">
var isInIFrame = (self != top);
$('#<%= hfIsInIframe.ClientID %>').val(isInIFrame);
</script>
Then you can check easily if it's an iFrame in the code-behind:
bool bIsInIFrame = (hfIsInIframe.Value == "true");
Tested and worked for me.
Edit: Please note that you require jQuery to run my code above. To run it without jQuery just use some code like the following (untested) code to set the value of the hidden field:
document.getElementById('<%= hfIsInIframe.ClientID %>').value = isInIFrame;
Edit 2: This only works when the page was loaded once. If someone have idea's to improve this, let me know. In my case I luckily only need the value after an postback.
There is no way of checking this that will fit your requirement of "secure" as stated in your comment on #WTP's answer.
I don't think the server-side can do this, so why not put a hidden control in your page that will be in the iframe? When the URL in the iframe loads, you can add some client-side code to set the hidden input to indicate you are in an iframe. The easiest check would be on the client-side in an onload method, like this:
// Set hidden input
someHiddenInput.value = self != top
It's more secure than the querystring, but it still might not be enough security for you.
My 2 cents.
Old question but why not a more simplistic approach like
var isFramed = self !== parent
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>