On exit page event

[Peter Larsen [CPH]]

Hi,

How do i track when i move away from a page - aka "window.onbefor eunload",
but on server side.

If you think of a sample where you have some textbox's and you want to get
the contents, before moving away from the page, but you don't want to use
post-back on each textbox. How is that done ??

At the moment, i'm trying an idea where i use the following script in on
window.onbefore unload. This gives me a postback where i have the opportunity
to read from the page before moving away (or if a button is pushed and
similar stuff).

function doOnBeforeUnloa d()
{
__doPostBack('n othing', '');
}

But i am not sure what the consequences are, using this method. Do i break
something or is it a possible solution ??
There is one problem though - if using session states, data could be
overwritten with data from older pages. But that could be solved by writing
a timestamp to the page.

So, is postback a solution or are there other ways to do this ??

Best Regards
Peter

[Mark Rae [MVP]]

Re: On exit page event

"Peter Larsen [CPH]" <PeterLarsen@co mmunity.nospamw rote in message
news:eB4IaCqGJH A.3628@TK2MSFTN GP06.phx.gbl...

How do i track when i move away from a page - aka "window.onbefor eunload",
but on server side.

Reliably, you can't. This is a very common question in web development, and
the problem is the inherent disconnected architecture of browser-based
applications.

Specifically:
a) a web browser sends an HttpRequest to a web server
b) the web server processes that HttpRequest and sends back an HttpResponse
c) the web browser receives the HttpResponse and renders the HTML

At this point, the web server has no way of knowing what happens until /
unless it receives another HttpRequest from the web browser because there is
no permanent connection between web server and web browser. A common analogy
is a letter in the post; if you send me a letter, you have no further
knowledge of what happens to that letter once it's left your hand. You can't
know whether I read it, whether I throw it away or if I've even received it.
Unless I tell you!

If you think of a sample where you have some textboxes and you want to get
the contents before moving away from the page, but you don't want to use
post-back on each textbox. How is that done ??

So, is postback a solution or are there other ways to do this ??

Postback is a possible solution, but bear in mind that the onbeforeunload /
beforeunload will fire *every time* the page closes...


--
Mark Rae
ASP.NET MVP

http://www.markrae.net

[Peter Larsen [CPH]]

Re: On exit page event

Hi Mark and thanks for your comments.

The alternative is a popup message on onbeforeunload, but that leaves me
with other problems (like getting too many popups) !

Calling __doPostBack from onbeforeunload looks very similar to a normal
button click (postback) where the control hasn't no OnClick method assigned
to it. The only difference is that the event also will be fired when you
close the tab or browse to a new page.

To me it sounds like a win-win - except that i should be more careful about
not getting newer data destroyed by older data.

Postback is a possible solution, but bear in mind that the onbeforeunload
/ beforeunload will fire *every time* the page closes...

What do you mean about "every time" ??

BR
Peter



"Mark Rae [MVP]" <mark@markNOSPA Mrae.netwrote in message
news:%239SEnhqG JHA.3460@TK2MSF TNGP04.phx.gbl. ..

"Peter Larsen [CPH]" <PeterLarsen@co mmunity.nospamw rote in message
news:eB4IaCqGJH A.3628@TK2MSFTN GP06.phx.gbl...
>

[Mark Rae [MVP]]

Re: On exit page event

"Peter Larsen [CPH]" <PeterLarsen@co mmunity.nospamw rote in message
news:%23j9SKKrG JHA.4760@TK2MSF TNGP05.phx.gbl. ..

Calling __doPostBack from onbeforeunload looks very similar to a normal
button click (postback) where the control hasn't no OnClick method
assigned to it. The only difference is that the event also will be fired
when you close the tab or browse to a new page.

That's right - extremely irritating...

>Postback is a possible solution, but bear in mind that the onbeforeunload
>/ beforeunload will fire *every time* the page closes...

>
What do you mean about "every time" ??

Exactly what I say... Every time, not necessarily just when you want it, but
every time...


--
Mark Rae
ASP.NET MVP

http://www.markrae.net

[Peter Larsen [CPH]]

Re: On exit page event

Hi Mark,

Do you know of a better way to accomplish this (save data before exit) ??

/Peter

"Mark Rae [MVP]" <mark@markNOSPA Mrae.netwrote in message
news:Oj3qUbrGJH A.2236@TK2MSFTN GP05.phx.gbl...

"Peter Larsen [CPH]" <PeterLarsen@co mmunity.nospamw rote in message
news:%23j9SKKrG JHA.4760@TK2MSF TNGP05.phx.gbl. ..
>

>Calling __doPostBack from onbeforeunload looks very similar to a normal
>button click (postback) where the control hasn't no OnClick method
>assigned to it. The only difference is that the event also will be fired
>when you close the tab or browse to a new page.

>
That's right - extremely irritating...
>

>>Postback is a possible solution, but bear in mind that the
>>onbeforeunloa d / beforeunload will fire *every time* the page closes...

>>
>What do you mean about "every time" ??

>
Exactly what I say... Every time, not necessarily just when you want it,
but every time...
>
>
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Mark Rae [MVP]]

Re: On exit page event

"Peter Larsen [CPH]" <PeterLarsen@co mmunity.nospamw rote in message
news:Ojp5JWwGJH A.3668@TK2MSFTN GP02.phx.gbl...

[please don't top-post]

>>Calling __doPostBack from onbeforeunload looks very similar to a normal
>>button click (postback) where the control hasn't no OnClick method
>>assigned to it. The only difference is that the event also will be fired
>>when you close the tab or browse to a new page.

>>
>That's right - extremely irritating...
>>

>>>Postback is a possible solution, but bear in mind that the
>>>onbeforeunlo ad / beforeunload will fire *every time* the page closes...
>>>
>>What do you mean about "every time" ??

>>
>Exactly what I say... Every time, not necessarily just when you want it,
>but every time...

>
Do you know of a better way to accomplish this (save data before exit) ??

No.


--
Mark Rae
ASP.NET MVP

http://www.markrae.net