Can I create an ASP.NET ImageButton that doesn't postback? - asp.net

I'm trying to use the ImageButton control for client-side script execution only. I can specify the client-side script to execute using the OnClientClick property, but how do I stop it from trying to post every time the user clicks it? There is no reason to post when this button is clicked. I've set CausesValidation to False, but this doesn't stop it from posting.

I know this problem has already been answered but a simple solution is to return false from the HTML onclick method (i.e. the ASPX OnClientClick method) e.g.
<asp:ImageButton ID="ImageNewLink" runat="server"
ImageUrl="~/images/Link.gif" OnClientClick="DoYourStuff(); return false;" />
Returning false stops the browser from making the request back to the server i.s. stops the .NET postback.

Here's one way you could do it without conflicting with the postback functioning of other controls:
Define your button something like this:
<asp:Button runat="server" Text="Button" UseSubmitBehavior="false" OnClientClick="alert('my client script here');my" />
The "my" ending in the handler for OnClientClick is a way to alias asp.net's __doPostBack client event that forces the postback; we simply override the behavior by doing nothing similar to this script:
<script type="text/javascript">
function my__doPostBack(eventTarget, eventArgument) {
//Just swallow the click without postback of the form
}
</script>
Edit: Yeesh, I feel like I need to take a shower after some of the dirty tricks that I need to pull in order to get asp.net to do what I want.

Another solution would be to define a PostBackUrl that does nothing
<asp:imagebutton runat="server" PostBackUrl="javascript:void(0);" .../>

<image src="..." onclick="DoYourThing();" />

Use a server side Image control
<asp:Image runat="server" .../>
Pretty sure you can add the client onclick event to that.

Solution 1
<asp:ImageButton ID="btn" runat="server" ImageUrl="~/images/yourimage.jpg"
OnClientClick="return false;" />
OR
Solution 2
<asp:ImageButton ID="btn" runat="server" ImageUrl="~/images/yourimage.jpg"
OnClientClick="yourmethod(); return false;" />
In addition (solution 2), your javascript method may be in this form
<script type="text/javascript">
function yourmethod() {
__doPostBack (__EVENTTARGET,__EVENTARGUMENT); //for example __doPostBack ('idValue',3);
}
</script>
in code behind
protected void Page_Load(object sender, System.EventArgs e)
{
if (this.IsPostBack) {
string eventTarget = this.Request("__EVENTTARGET") == null ? string.Empty : this.Request("__EVENTTARGET");
string eventArgument = this.Request("__EVENTARGUMENT") == null ? string.Empty : this.Request("__EVENTARGUMENT");
}
}

This works Great for me:
Use OnClientClick to write your script and PostBackUrl="javascript:void(0);" to avoid postback.
<div class="close_but">
<asp:ImageButton ID="imgbtnEChartZoomClose" runat="server" ImageUrl="images/close.png" OnClientClick="javascript:zoomclosepopup();" PostBackUrl="javascript:void(0);" />
</div>

Use OnClientClick to write your script and PostBackUrl="javascript:void(0);" to avoid postback

Related

Disable server side of asp.net button

How to disable button callback, I want to use this button on client side only?
<dx:ASPxButton ID="btn_clear" runat="server"
Text="Clear" Width="90px" OnClick="btn_clear_Click">
<ClientSideEvents Click = "OnClick" />
</dx:ASPxButton>
onClientClick=return false will prevent processing the normal postback. If you want to do some custome javascript at client side, you can call return false after that
<asp:Button id="btn1" runat="server" onClientClick="return MyFunction" />
And in javascript
function MyFunction()
{
//Do your custom code
return false;
}
Judging by your button tag prefix it looks as though you're using Devexpress components not a normal asp.net button. Devexpress' ASPxButton control client click event has a processOnServer property which you can set to false to prevent a postback:
<dx:ASPxButton ID="btn_clear" runat="server"
Text="Clear" Width="90px" OnClick="btn_clear_Click">
<ClientSideEvents Click = "OnClick" />
</dx:ASPxButton>
and your OnClick() javascript function:
function OnClick(s, e)
{
e.processOnServer = false;
}
Without using third party components, if you want a button to just do something client side, then just use a HTML input button but if you want to have the client side capabilities of the asp.net button at your disposal (such as causing validation) then Shyju's answer is the way to go.
Hwo about simply removing the OnClick Handler ?
<dx:ASPxButton ID="btn_clear" runat="server"
Text="Clear" Width="90px">
<ClientSideEvents Click = "OnClick" />
</dx:ASPxButton>
Or even better, just use a HTML button in the first place (<input type="button" />).
You can't.
Server side controls must run on the server side.
If you omit the runat="server" attribute, the markup will render exactly like this:
<dx:ASPxButton ID="btn_clear"
Text="Clear" Width="90px" OnClick="btn_clear_Click">
<ClientSideEvents Click = "OnClick" />
</dx:ASPxButton>
This will be completely ignored by the browser, as an element dx:ASPxButton is not a valid HTML element.
Just add an attribute AutoPostBack="false", this will stop the postback, still you need to call server side function using client side script, you can use callback panels

imagebutton with onclientclick isn't firing onclick event

I have an imagebutton with an postbackurl and an onclientclick script. When i added the onclientclick code, if my javascript validation passes (aka returns true), the page just seems to perform a postback (the screen just seems to refresh itself), rather than post to the postbackurl. Any ideas why this is happening?
Sample:
<asp:ImageButton ID="imgSendInfo" runat="server" SkinID="SendInfo" PostBackUrl="MyUrlOnAnotherSite" onClientClick="javascript:return onFormSubmit(this.form);return document.MM_returnValue" />
UPDATE:
OK, so I decided to change what JS functions I'm calling now since calling Multiple functions definitely wasn't helping. Here's my updated code. All I'm doing now is validating a single textbox and returning true or false. Even this simple function is causing the postback URL to never get called. Could it have anything to do with the fact that I'm trying to call a function to return a true or false?
My validation function:
function valForm() {
if (document.getElementById('FName').value == '') {
alert('no');
return false;
}
else {
alert('yes');
return true;
}
}
My ImageButton:
<asp:ImageButton ID="imgSendInfo" runat="server" SkinID="SendInfo" PostBackUrl="SetOnCodeBehind" onClientClick="javascript:return valForm();" />
OK figured out a workaround. I REMOVED the return statement from the onclientclick, since the return is what was messing with the postback. I then added requiredfieldvalidators to the page, but Im not displaying any text. This way, 2 sets of validation are occurring (booo), but the first displays my alert messages (this is how the client wants validation performed), and the second prevents the form from posting.
My imagebutton:
<asp:ImageButton ID="imgSendInfo" runat="server" SkinID="SendInfo" PostBackUrl="SetOnCodeBehind" ValidationGroup="enroll" CausesValidation="true" onClientClick="javascript:onFormSubmit(this.form);document.MM_returnValue;" />
My requiredfieldvalidation group:
<asp:RequiredFieldValidator ID="reqVal1" runat="server" ErrorMessage="" ValidationGroup="enroll" ControlToValidate="FName" InitialValue="" />
<asp:RequiredFieldValidator ID="reqVal2" runat="server" ErrorMessage="" ValidationGroup="enroll" ControlToValidate="LName" InitialValue="" />
Did you know that your onClientClick js-function returns twice? return document.MM_returnValue never gets reached.
Is your PostBackUrl's page in your application? You can even validate the previous page on serverside:
If Page.PreviousPage.IsValid Then
' Handle the post back
Else
Response.Write("Invalid")
End If
For further information: MSDN LinkButton.PostBackUrl

javascript __doPostBack doesn't seem to work for me

I use yui datatable in my asp.net application... I have a link button in one of my columns and it works fine but doesn't do a postback of a hidden button...
myDataTable.subscribe("linkClickEvent", function(oArgs) {
javascript: __doPostBack('ctl00_ContentPlaceHolder1_Button1', '');
YAHOO.util.Event.stopEvent(oArgs.event);
});
and in my page
<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button"
style="display:none;" />
protected void Button1_Click(object sender, EventArgs e)
{
DownloadFile(Hfhref.Value, true);
}
I used break point but it doesn't seem to get the __dopostback.. Any suggestion...
add unique id on __doPostBackMethod from Button.
I just did this and it worked,
document.getElementById("ctl00_ContentPlaceHolder1_Button1").click();
just call click() my button it worked...
I want to know whether it works in all browsers...
If you're using ASP.Net 4.0 framework, add ClientIDMode="Static" to your control declaration and you can call __doPostBack('Button1',''); directly.
<asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button"
style="display:none;" ClientIDMode="Static" />
The ClientIDMode attribute is new to 4.0 and allows you the option of having a known unique id for controls. Calling postback for the control will run whatever postback method is defined in the control's OnClick attribute.
In your markup, make sure to properly case the OnClick handler.
onclick="Button1_Click"
should be
OnClick="Button1_Click"
The way you have written it, onclick will be interpreted as an attribute of the control and onclick="Button1_Click" will be rendered to the browser, instead of being handled on the server side.

OnClick vs OnClientClick for an asp:CheckBox?

Does anyone know why a client-side javascript handler for asp:CheckBox needs to be an OnClick="" attribute rather than an OnClientClick="" attribute, as for asp:Button?
For example, this works:
<asp:CheckBox runat="server" OnClick="alert(this.checked);" />
and this doesn't (no error):
<asp:CheckBox runat="server" OnClientClick="alert(this.checked);" />
but this works:
<asp:Button runat="server" OnClientClick="alert('Hi');" />
and this doesn't (compile time error):
<asp:Button runat="server" OnClick="alert('hi');" />
(I know what Button.OnClick is for; I'm wondering why CheckBox doesn't work the same way...)
That is very weird. I checked the CheckBox documentation page which reads
<asp:CheckBox id="CheckBox1"
AutoPostBack="True|False"
Text="Label"
TextAlign="Right|Left"
Checked="True|False"
OnCheckedChanged="OnCheckedChangedMethod"
runat="server"/>
As you can see, there is no OnClick or OnClientClick attributes defined.
Keeping this in mind, I think this is what is happening.
When you do this,
<asp:CheckBox runat="server" OnClick="alert(this.checked);" />
ASP.NET doesn't modify the OnClick attribute and renders it as is on the browser. It would be rendered as:
<input type="checkbox" OnClick="alert(this.checked);" />
Obviously, a browser can understand 'OnClick' and puts an alert.
And in this scenario
<asp:CheckBox runat="server" OnClientClick="alert(this.checked);" />
Again, ASP.NET won't change the OnClientClick attribute and will render it as
<input type="checkbox" OnClientClick="alert(this.checked);" />
As browser won't understand OnClientClick nothing will happen. It also won't raise any error as it is just another attribute.
You can confirm above by looking at the rendered HTML.
And yes, this is not intuitive at all.
Because they are two different kinds of controls...
You see, your web browser doesn't know about server side programming. it only knows about it's own DOM and the event models that it uses... And for click events of objects rendered to it. You should examine the final markup that is actually sent to the browser from ASP.Net to see the differences your self.
<asp:CheckBox runat="server" OnClick="alert(this.checked);" />
renders to
<input type="check" OnClick="alert(this.checked);" />
and
<asp:CheckBox runat="server" OnClientClick="alert(this.checked);" />
renders to
<input type="check" OnClientClick="alert(this.checked);" />
Now, as near as i can recall, there are no browsers anywhere that support the "OnClientClick" event in their DOM...
When in doubt, always view the source of the output as it is sent to the browser... there's a whole world of debug information that you can see.
You are right this is inconsistent. What is happening is that CheckBox doesn't HAVE an server-side OnClick event, so your markup gets rendered to the browser. http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.checkbox_events.aspx
Whereas Button does have a OnClick - so ASP.NET expects a reference to an event in your OnClick markup.
For those of you who got here looking for the server-side OnClick handler it is OnCheckedChanged
I was cleaning up warnings and messages and see that VS does warn about it:
Validation (ASP.Net): Attribute 'OnClick' is not a valid attribute of element 'CheckBox'. Use the html input control to specify a client side handler and then you won't get the extra span tag and the two elements.
Asp.net CheckBox is not support method OnClientClick.
If you want to add some javascript event to asp:CheckBox you have to add related attributes on "Pre_Render" or on "Page_Load" events in server code:
C#:
private void Page_Load(object sender, EventArgs e)
{
SomeCheckBoxId.Attributes["onclick"] = "MyJavaScriptMethod(this);";
}
Note: Ensure you don't set AutoEventWireup="false" in page header.
VB:
Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
SomeCheckBoxId.Attributes("onclick") = "MyJavaScriptMethod(this);"
End Sub
You can do the tag like this:
<asp:CheckBox runat="server" ID="ckRouteNow" Text="Send Now" OnClick="checkchanged(this)" />
The .checked property in the called JavaScript will be correct...the current state of the checkbox:
function checkchanged(obj) {
alert(obj.checked)
}
You can assign function to all checkboxes then ask for confirmation inside of it. If they choose yes, checkbox is allowed to be changed if no it remains unchanged.
In my case I am also using ASP .Net checkbox inside a repeater (or grid) with Autopostback="True" attribute, so on server side I need to compare the value submitted vs what's currently in db in order to know what confirmation value they chose and update db only if it was "yes".
$(document).ready(function () {
$('input[type=checkbox]').click(function(){
var areYouSure = confirm('Are you sure you want make this change?');
if (areYouSure) {
$(this).prop('checked', this.checked);
} else {
$(this).prop('checked', !this.checked);
}
});
});
<asp:CheckBox ID="chk" AutoPostBack="true" onCheckedChanged="chk_SelectedIndexChanged" runat="server" Checked='<%#Eval("FinancialAid") %>' />
protected void chk_SelectedIndexChanged(Object sender, EventArgs e)
{
using (myDataContext db = new myDataDataContext())
{
CheckBox chk = (CheckBox)sender;
RepeaterItem row = (RepeaterItem) chk.NamingContainer;
var studentID = ((Label) row.FindControl("lblID")).Text;
var z = (from b in db.StudentApplicants
where b.StudentID == studentID
select b).FirstOrDefault();
if(chk != null && chk.Checked != z.FinancialAid){
z.FinancialAid = chk.Checked;
z.ModifiedDate = DateTime.Now;
db.SubmitChanges();
BindGrid();
}
gvData.DataBind();
}
}
One solution is with JQuery:
$(document).ready(
function () {
$('#mycheckboxId').click(function () {
// here the action or function to call
});
}
);

Disable the postback on an <ASP:LinkButton>

I have an ASP.NET linkbutton control on my form. I would like to use it for javascript on the client side and prevent it from posting back to the server. (I'd like to use the linkbutton control so I can skin it and disable it in some cases, so a straight up tag is not preferred).
How do I prevent it from posting back to the server?
ASPX code:
<asp:LinkButton ID="someID" runat="server" Text="clicky"></asp:LinkButton>
Code behind:
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
someID.Attributes.Add("onClick", "return false;");
}
}
What renders as HTML is:
<a onclick="return false;" id="someID" href="javascript:__doPostBack('someID','')">clicky</a>
In this case, what happens is the onclick functionality becomes your validator. If it is false, the "href" link is not executed; however, if it is true the href will get executed. This eliminates your post back.
This may sound like an unhelpful answer ... But why are you using a LinkButton for something purely client-side? Use a standard HTML anchor tag and set its onclick action to your Javascript.
If you need the server to generate the text of that link, then use an asp:Label as the content between the anchor's start and end tags.
If you need to dynamically change the script behavior based on server-side code, consider asp:Literal as a technique.
But unless you're doing server-side activity from the Click event of the LinkButton, there just doesn't seem to be much point to using it here.
You can do it too
...LinkButton ID="BtnForgotPassword" runat="server" OnClientClick="ChangeText('1');return false"...
And it stop the link button postback
Just set href="#"
<asp:LinkButton ID="myLink" runat="server" href="#">Click Me</asp:LinkButton>
I think you should investigate using a HyperLink control. It's a server-side control (so you can manipulate visibility and such from code), but it omits a regular ol' anchor tag and doesn't cause a postback.
Just been through this, the correct way to do it is to use:
OnClientClick
return false
as in the following example line of code:
<asp:LinkButton ID="lbtnNext" runat="server" OnClientClick="findAllOccurences(); return false;" />
In C#, you'd do something like this:
MyButton.Attributes.Add("onclick", "put your javascript here including... return false;");
Instead of implement the attribute:
public partial class _Default : System.Web.UI.Page{
protected void Page_Load(object sender, EventArgs e)
{
someID.Attributes.Add("onClick", "return false;");
}}
Use:
OnClientClick="return false;"
inside of asp:LinkButton tag
To avoid refresh of page, if the return false is not working with asp:LinkButton use
href="javascript: void;"
or
href="#"
along with OnClientClick="return false;"
<asp:LinkButton ID="linkPrint" runat="server" CausesValidation="False" href="javascript: void;"
OnClientClick="javascript:self.print();return false;">Print</asp:LinkButton>
Above is code will call the browser print without refresh the page.
call java script function on onclick event.
Have you tried to use the OnClientClick?
var myLinkButton = new LinkButton { Text = "Click Here", OnClientClick = "JavaScript: return false;" };
<asp:LinkButton ID="someID" runat="server" Text="clicky" OnClientClick="JavaScript: return false;"></asp:LinkButton>
Something else you can do, if you want to preserve your scroll position is this:
<asp:LinkButton runat="server" id="someId" href="javascript: void;" Text="Click Me" />
Why not use an empty ajax update panel and wire the linkbutton's click event to it? This way only the update panel will get updated, thus avoiding a postback and allowing you to run your javascript
No one seems to be doing it like this:
createEventLinkButton.Attributes.Add("onClick", " if (this.innerHTML == 'Please Wait') { return false; } else { this.innerHTML='Please Wait'; }");
This seems to be the only way that works.
In the jquery ready function you can do something like below -
var hrefcode = $('a[id*=linkbutton]').attr('href').split(':');
var onclickcode = "javascript: if`(Condition()) {" + hrefcode[1] + ";}";
$('a[id*=linkbutton]').attr('href', onclickcode);
You might also want to have the client-side function return false.
<asp:LinkButton runat="server" id="button" Text="Click Me" OnClick="myfunction();return false;" AutoPostBack="false" />
You might also consider:
<span runat="server" id="clickableSpan" onclick="myfunction();" class="clickable">Click Me</span>
I use the clickable class to set things like pointer, color, etc. so that its appearance is similar to an anchor tag, but I don't have to worry about it getting posted back or having to do the href="javascript:void(0);" trick.
use html link instead of asp link and you can use label in between html link for server side
control

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