Lawrence San wrote:
I'm trying to test some simple JavaScript meant to speed up the display
of my Web pages for readers using modems, but I have a fast DSL
connection and I'm having trouble visualizing how effective the code
is. Does anybody know of software that will simulate modem speed over a
DSL connection -- i.e., temporarily slow down the speed of my
connection, or the speed at which the browser uses the connection? (I
author on a Mac but test on a PC -- I'm mostly interested in slowing
down IE6 on Windows since that's what most people use.) I've searched
but could not find such software. (I don't have a real 56K modem that
can be used for this purpose.)
My second question involves actually looking at the list of files that
have loaded into the browser's cache. Windows IE6 seems to be the only
one of my test browsers that lets me do this. Mac IE5 puts all the
cache files into one big file that's opaque to me; Windows Netscape 6
loads them as separate files, but renames the cache files to gibberish
that I can't decipher.
Is there a way to actually see what files are getting cached in these
other browsers? Am I missing something?
Thanks much,
San
What gets cached is a combination of server headers, intervening proxies
and client user agent settings. You can only control the server headers to
ensure that .js files are not configured to send "Expires: ...",
"Cache-control: ... " or "Pragma: no-cache" headers (or if the server is
sending Cache-control: headers, they are correct) <url:
http://www.mnot.net/cache_docs/#CONTROL />. My guess is that your server is
configured correctly, it would take explicit action on the part of the Web
server administrator to change those settings.
You have no control over what any proxies between your server and the
client might do, so I won't bother discussing it (although you *can*
control some proxies to some extent with appropriate Cache-control: server
headers).
That leaves client user agent cache settings, which you also have NO
control over. However, as long as the user has left the user agent
(browser) configured as installed, the browser will be caching any files
you send it.
IE: Tools -> Internet Options -> General tab -> Settings -> Automatically
Netscape 4: Edit -> Preferences -> Advanced -> Cache -> Once per session
Firefox: No internal setting to control caching, but there are Extensions
that can provide this functionality. From my use of this browser, it's
obvious to me it refreshes the local cached copy when it detects the server
copy is out of date.
Mozilla 1.6: Edit -> Preferences -> Advanced -> Cache -> When the page is
out of date
Opera 7.5: Tools -> Preferences -> Network -> History and cache -> Check
documents, Check images, Check other (which is the dopiest way to handle
caching I've ever seen, but whatever)
etc
etc
etc
As you can see, and as I said, all you can control is the server. Ensure it
is configured correctly. After that, caching behaviour will be the combined
result of any proxies the page has to pass through and the client's user
agent cache settings. If the user has their user agent configured
correctly, it will cache, if they don't, it won't.
--
| Grant Wagner <gw*****@agrico reunited.com>
* Client-side Javascript and Netscape 4 DOM Reference available at:
*
http://devedge.netscape.com/library/...ce/frames.html
* Internet Explorer DOM Reference available at:
*
http://msdn.microsoft.com/workshop/a...ence_entry.asp
* Netscape 6/7 DOM Reference available at:
*
http://www.mozilla.org/docs/dom/domref/
* Tips for upgrading JavaScript for Netscape 7 / Mozilla
*
http://www.mozilla.org/docs/web-deve...upgrade_2.html 
