Well there is a couple of ways to do it....

Personally if you dont have alot of these elements then 2 hidden elements 
within the div or page that hold (A) last Ajax.Request time and (B) last 
change time


then just listen to every input element inside the div for a change 
(untested)

$$('#mydiv input').invoke('observe','change',function(element) {

        $('thehiddenelement').value=the_time_it_was_updated;

});
then you can check that on the request function and see if its needed to be 
sent or not ... (this is a hack!!)

Another way is to create a cache on page load of every input element on the 
page and add it to an array or a json object and store its id,parent,value 
in the array...

HTH

Alex





----- Original Message ----- 
From: "Aamchi" <aman.ra...@googlemail.com>
To: "Prototype & script.aculo.us" <prototype-scriptaculous@googlegroups.com>
Sent: Wednesday, June 24, 2009 8:40 AM
Subject: [Proto-Scripty] Re: Periodical Updater detect content change



I thought of that too. But this only works in forms doesn't it? How do
I detect a changed within a <div> which is reloaded every few seconds?
Would you mind sending me an example?
Thanks,
Aman

On 24 Jun., 08:36, "Alex McAuley" <webmas...@thecarmarketplace.com>
wrote:
> There is also a 
> Form.observerhttp://www.prototypejs.org/api/timedObserver/form-observer
> I used to use this but implemented my own version of it with a cache and
> some hashing, it didnt take long to write and works perfectly
>
> HTH
> Alex
>
> ----- Original Message -----
> From: "Aamchi" <aman.ra...@googlemail.com>
> To: "Prototype & script.aculo.us" 
> <prototype-scriptaculous@googlegroups.com>
> Sent: Tuesday, June 23, 2009 11:19 PM
> Subject: [Proto-Scripty] Re: Periodical Updater detect content change
>
> Thanks, for your response. I'm not 100% sure if I understand correctly
> what you mean. If I get some data and generate a hash and write this
> to the JSON header and retrieve this when calling onSuccess, how will
> I still have the previous hash? From where will I get this? Won't the
> updated data cause the hash to be overwritten in the JSON header? Or
> do I have to send two hashes always and compare them?
>
> On 23 Jun., 22:57, Richard Quadling <rquadl...@googlemail.com> wrote:
> > 2009/6/23 Aamchi <aman.ra...@googlemail.com>
>
> > > Hi,
>
> > > I was wondering if Ajax.PeriodicalUpdater can detect if content has
> > > changed since the last update and if so trigger an event.
>
> > > So for example I have a scoreboard which fetches data every 5 seconds
> > > and displays this. I would be cool if there could be some kind of
> > > notification if content had changed. I know that the new content is
> > > stores in responseText but how can I compare it to the previous
> > > content...
>
> > > Thanks,
> > > Aman
>
> > Personally, I would do this server side.
> > Assuming you get the data in some sort of structure before either 
> > rending
> > some HTML and sending it or just sending it JSON'd, then you should be
> > able
> > to build a hash of the data.
>
> > See [1] for info on Hash Functions.
>
> > So. If you sent the hash value in a X-JSON header along with an
> > onSuccess()
> > callback, you can extract the hash from the second param to the 
> > onSuccess
> > and compare this with the previously retrieved hash to indicate you've 
> > got
> > changed data. See [2] for details about PeriodicalUpdater update
> > notification and [3] for the parameters to common callbacks.
>
> > Regards,
>
> > Richard.
>
> > [1]http://en.wikipedia.org/wiki/Hash_function
> > [2]http://www.prototypejs.org/api/ajax/periodicalUpdater
> > <http://www.prototypejs.org/api/ajax/periodicalUpdater>[3]http://www.prototypejs.org/api/ajax/options
> > <http://www.prototypejs.org/api/ajax/options>
>
> > --
> > -----
> > Richard Quadling
> > Zend Certified Engineer 
> > :http://zend.com/zce.php?c=ZEND002498&r=213474731
> > "Standing on the shoulders of some very clever giants!"



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