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Scripted Updated Indicator

P: n/a
I use the following piece of code to show when the page thats being accessed was
last updated:

<!--
var modified = new Date(document.lastModified);
document.write("<b>Last Updated:<i> "+modified+"</I></B>");
// -->

This works great, but it only does it for the page thats currently displayed.

Is there some way to possibly get my main page to show an updated indicator
likie:
some page link <UPDATED> then date/time

Where <updated> is an animated gif I use that flashes updated.

I've been doing this by hand for my main page, but would like to automate it so
that if the page has been updated within say the last 5 days it would
automatically add this flashing graphic and the date/time next to the link for
the page.

Thanks for any pointers.

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Jul 23 '05 #1
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P: n/a
xx***********@tampascanner.info wrote:
I use the following piece of code to show when the page thats being accessed was
last updated:

<!--
var modified = new Date(document.lastModified);
document.write("<b>Last Updated:<i> "+modified+"</I></B>");
// -->
Hiding scripts is unnecessary and potentially harmful, don't do it.

This works great, but it only does it for the page thats currently displayed.
It will also only work if the user has JavaScript enabled. Not to be
picky, but why does it need to work on pages that aren't currently
displayed? :-)

Oh, I get it (I'm a bit slow this morning), you mean it doesn't work
for resources indicated by URI's.

So your dilema is that you want to determine the last modified date of
the resource at the end of the link, not the current document. And to
do that reliably is probably beyond the capability of any browser (note
that the content may have changed even if the actual HTML file that
hosts the content has not - e.g. modified images or dynamic content).

For more (general) information on lastModified, read the group FAQ:

<URL:http://www.jibbering.com/faq/#FAQ4_30>

Is there some way to possibly get my main page to show an updated indicator
likie:
some page link <UPDATED> then date/time

Where <updated> is an animated gif I use that flashes updated.
Flashing gifs ...ugghhh! They are truely despised, please reconsider.
Also, if the user has images turned off, they won't see the gif.

Anyway, let's proceed on the assumption that you will just place an
attractive 'New' gif (or just coloured text) next to links that point
to content less than 5 days old.

How you determine the period depends on how accurately you want to
measure your 5 days. By far the simplest method is to work it out at
your server and just add the appropriate highlight before sending the
page. You are then insulated from the vaguaries of client systems and
the accuracy of their internal clock.

If you're going to trust the client system's clock, you can send a date
object in your file, create a 'now' date object at the client, convert
them both to the same reference system (say UTC), find the difference
and if it's greater than 4.32e8 (the number milliseconds in 5 days)
show the highlight. That is likely not exact, but near enough for
now.

You could include a string in the value of some attribute of each link
(say in the class) that represents the date last modified of the linked
resource and can be converted into a date object. A script could
extract the value, convert it, compare it to 'now' and conditionally
add the highlight.

But for all that effort you may as well just add the highlight at the
server instead of the embedded date string, avoiding client-side
issues. Your server can get the last modified timestamp for linked
resources without your intervention, so that part is catered for too
(but the issue of updated content in the linked resource is not).

The server script would likely be no more complex than a client
script of similar functionality.

I've been doing this by hand for my main page, but would like to automate it so
that if the page has been updated within say the last 5 days it would
automatically add this flashing graphic and the date/time next to the link for
the page.


A client-side, script-dependant, unreliable solution is likely not
suitable when a better server side solution is availabe.
--
Fred
Jul 23 '05 #2

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