Is it possible to pre-empt the javascript function used to do a postback 
from a linkbutton?

I'd like to use linkbutton to delete a record and want to add a confirmation 
box via javascript "are you sure you want to delete this record?" before it 
executes the postback. The javascript is straightforward for this, but have 
no idea how to have that intercept the post-back script.

-Darrel

"darrel"  wrote in message 
news:%23z18k1U1HHA.3788@TK2MSFTNGP02.phx.gbl...


> Is it possible to pre-empt the javascript function used to do a postback 
> from a linkbutton?
>
> I'd like to use linkbutton to delete a record and want to add a 
> confirmation box via javascript "are you sure you want to delete this 
> record?" before it executes the postback. The javascript is 
> straightforward for this, but have no idea how to have that intercept the 
> post-back script.


Any JavaScript function which returns false will intercept a postback e.g.

<asp:Button ID="MyButton" runat="server" OnClick="MyButton_Click" 
OnClientClick="return confirm('Are you sure you want to delete this 
record?');" Text="Delete" />

In the above example, when a user clicks on the Delete button, they will be 
prompted with a client-side Yes/No alert - if they click Yes, the postback 
will happen and run the code in the server-side MyButton_Click method - if 
they click No, the postback will be intercepted and nothing further will 
happen...


-- 
Mark Rae
ASP.NET MVP
http://www.markrae.net

> <asp:Button ID="MyButton" runat="server" OnClick="MyButton_Click" 
> OnClientClick="return confirm('Are you sure you want to delete this 
> record?');" Text="Delete" />


Slick, but can this be done with a linkButton? I don't see an OnClientClick 
property for that.

-Darrel

"darrel"  wrote in message 
news:u98mrEV1HHA.3940@TK2MSFTNGP05.phx.gbl...


>> <asp:Button ID="MyButton" runat="server" OnClick="MyButton_Click" 
>> OnClientClick="return confirm('Are you sure you want to delete this 
>> record?');" Text="Delete" />
>
> Slick, but can this be done with a linkButton? I don't see an 
> OnClientClick property for that.


Yep - in the Page_Load, add the following code:

MyLinkButton.Attributes.Add("onclick", "return confirm('Are you sure you 
want to delete this record?');");


-- 
Mark Rae
ASP.NET MVP
http://www.markrae.net

> MyLinkButton.Attributes.Add("onclick", "return confirm('Are you sure you 
> want to delete this record?');");


Hmm...I've done that, but the event handler still executes for the 
linkButton regardless of whether I click OK or CANCEL in the confirmation 
window.

-Darrel

"darrel"  wrote in message 
news:OCA$zOV1HHA.3400@TK2MSFTNGP03.phx.gbl...


>> MyLinkButton.Attributes.Add("onclick", "return confirm('Are you sure you 
>> want to delete this record?');");
>
> Hmm...I've done that, but the event handler still executes for the 
> linkButton regardless of whether I click OK or CANCEL in the confirmation 
> window.


Actually, having just tried this, <asp:LinkButton> most certainly *does* 
have an OnClientClick property:
http://msdn2.microsoft.com/en-us/library/system.web.ui.webcontrols.linkbutton.onclientclick(vs.80).aspx


-- 
Mark Rae
ASP.NET MVP
http://www.markrae.net

On Aug 3, 6:34 am, "Mark Rae [MVP]"  wrote:

> "darrel"  wrote in message
>
> news:OCA$zOV1HHA.3400@TK2MSFTNGP03.phx.gbl...
>
> >> MyLinkButton.Attributes.Add("onclick", "return confirm('Are you sure you
> >> want to delete this record?');");
>
> > Hmm...I've done that, but the event handler still executes for the
> > linkButton regardless of whether I click OK or CANCEL in the confirmation
> > window.
>
> Actually, having just tried this, <asp:LinkButton> most certainly *does*
> have an OnClientClick property:http://msdn2.microsoft.com/en-us/library/system.web.ui.webcontrols.li...
>
> --
> Mark Rae
> ASP.NET MVPhttp://www.markrae.net



Hi guys, maybe Darrel is not using asp.net version 2.0, the msdn link
above says the onclientclick property is new for .Net framework
version 2.0 upwards. Anyway, to achieve the same effect using
javascript:

<script>
var mybutton = document.getElementById('linkButton1');
var oldonclickfunction = mybutton.onclick; //old postback method
mybutton.onclick=function() {
if(confirm('Are you sure you want to delete this record?'))
{oldonclickfunction();}
else{ return false;}
}
</script>

just need to replace linkButton1 with the button's id (extra caution
to make sure it's the control's unique hierarchically qualified id,
should be fine if the button is just on the form and not encapsulated
in a panel, table, grid or user control).

--
Collin

> Hi guys, maybe Darrel is not using asp.net version 2.0


Yes, apologies for not clarifying that.

This is still a 1.1 app we're maintaining.

2.0 is moving along with MOSS, but for now, we're still going to be doing a 
chunk of 1.1 work.


> Anyway, to achieve the same effect using
> javascript:
>
> <script>
> var mybutton = document.getElementById('linkButton1');
> var oldonclickfunction = mybutton.onclick; //old postback method
> mybutton.onclick=function() {
> if(confirm('Are you sure you want to delete this record?'))
> {oldonclickfunction();}
> else{ return false;}
> }
> </script>
>
> just need to replace linkButton1 with the button's id (extra caution
> to make sure it's the control's unique hierarchically qualified id,
> should be fine if the button is just on the form and not encapsulated
> in a panel, table, grid or user control).


Collin:

Don't I still need to apply some sort of onClick event to the linkButton, 
though? I'm not sure how the above script would know to intercept the 
onClick event if there's nothing to trigger it.

-Darrel

"darrel"  wrote in message 
news:Oe8lbzd1HHA.4672@TK2MSFTNGP05.phx.gbl...


> Don't I still need to apply some sort of onClick event to the linkButton, 
> though? I'm not sure how the above script would know to intercept the 
> onClick event if there's nothing to trigger it.


MyLinkButton.Attributes.Add("onclick", "return confirm('Are you sure you 
want to delete this record?');");


-- 
Mark Rae
ASP.NET MVP
http://www.markrae.net

> MyLinkButton.Attributes.Add("onclick", "return confirm('Are you sure you
> want to delete this record?');");


Well, this is where my lack of Javascript skills begins to show. ;0)

Here's the function I'm using curtesy of Collin:

 var mybutton = document.getElementById('lnkBtn_delete');
var oldonclickfunction = mybutton.onclick; //old postback method
mybutton.onclick=function() {
     if(confirm('Are you sure you want to delete this record?'))
        {oldonclickfunction();}
     else{ return false;}
     }

Right now, that's giving me a 'mybutton has no properties' javascript error.

Mark, your onclick event makes sense, but that same confirm is also 
executing in the script of collins, so it appears that I'm going to cause 
double-alerts in this case (provided I can get the 'mybutton has no 
properties' error fixed...)

-Darrel

"darrel"  wrote in message 
news:uxhAj5d1HHA.5796@TK2MSFTNGP05.phx.gbl...


> Well, this is where my lack of Javascript skills begins to show. ;0)
>
> Here's the function I'm using curtesy of Collin:
> Mark, your onclick event makes sense,


You can't have both...


-- 
Mark Rae
ASP.NET MVP
http://www.markrae.net

darrel wrote:

>> MyLinkButton.Attributes.Add("onclick", "return confirm('Are you sure
>> you want to delete this record?');");
>
> Well, this is where my lack of Javascript skills begins to show. ;0)
>
> Here's the function I'm using curtesy of Collin:
>
> var mybutton = document.getElementById('lnkBtn_delete');
> var oldonclickfunction = mybutton.onclick; //old postback method


Isn't JavaScript case-sensitive, so onclick should be onClick?

Andrew

>> Here's the function I'm using curtesy of Collin:
>> Mark, your onclick event makes sense,
>
> You can't have both...


Right. But that's kind of going back to my original problem...adding the 
confirmation on the OnClick event of the linkbutton does NOT intercept the 
postback. Regardless of whether or not I click OK or CANCEL, the postback is 
still executed.

-Darrel

> Isn't JavaScript case-sensitive, so onclick should be onClick?


'doh! yea, good catch!

That said, I still get the 'mybutton has no properties' error.

-Darrel

"darrel"  wrote in message 
news:%23mxBCge1HHA.4476@TK2MSFTNGP06.phx.gbl...


>>> Here's the function I'm using curtesy of Collin:
>>> Mark, your onclick event makes sense,
>>
>> You can't have both...
>
> Right. But that's kind of going back to my original problem...adding the 
> confirmation on the OnClick event of the linkbutton does NOT intercept the 
> postback. Regardless of whether or not I click OK or CANCEL, the postback 
> is still executed.


It's working perfectly for me, although I am of course using ASP.NET v2. I 
don't recall there being any problems in v1.x, though... Here's the code I'm 
using:

<asp:LinkButton ID="lnkButton" runat="server" OnClick="lnkButton_Click" 
OnClientClick="return confirm('Are you sure you want to delete this 
record?');" Text="Delete" />

protected void lnkButton_Click(object sender, EventArgs e)
{
    string strTest = String.Empty;
}


-- 
Mark Rae
ASP.NET MVP
http://www.markrae.net

> It's working perfectly for me, although I am of course using ASP.NET v2. I 
> don't recall there being any problems in v1.x, though... Here's the code 
> I'm using:
>
> <asp:LinkButton ID="lnkButton" runat="server" OnClick="lnkButton_Click" 
> OnClientClick="return confirm('Are you sure you want to delete this 
> record?');" Text="Delete" />


Seems like 2.0 has a more intuitive 'OnClientClick' event.

If I apply the confirmation to the OnClick event in 1.1, the alert box 
works...it just doesn't stop the postback from executing.

-Darrel

"darrel"  wrote in message 
news:eO4$mBf1HHA.4916@TK2MSFTNGP03.phx.gbl...


> Seems like 2.0 has a more intuitive 'OnClientClick' event.
>
> If I apply the confirmation to the OnClick event in 1.1, the alert box 
> works...it just doesn't stop the postback from executing.


Fair enough - unfortunately, I can't confirm this as I retired my one 
remaining v1.1 installation quite a few months ago...


-- 
Mark Rae
ASP.NET MVP
http://www.markrae.net

> Fair enough - unfortunately, I can't confirm this as I retired my one
> remaining v1.1 installation quite a few months ago...


I don't blame you. ;o)

-Darrel

> If I apply the confirmation to the OnClick event in 1.1, the alert box 
> works...it just doesn't stop the postback from executing.


....CUASE I'M AN IDIOT!

doh'...finally realized it wasn't working because I forgot to put the RETURN 
in there before the confirm command.

Sorry...USER ERROR!

Thanks for all the help Mark and Collin!

-Darrel