检测IE设置：“从不”检查存储页面的较新版本

Question

I understand there isn't a way to interrogate a users IE settings directly due to security reasons, but is there a way to derive this answer with some other mechanism? I would like to stop a user from using my site if the setting "Check for newer versions of stored pages" is set to "Never". Any suggestions?

Is there a way I could test for this using javascript? An example of what I am trying to accomplish is this: While it is not possible to check IE settings to see if you are running a popup blocker, that is a way to "test" for a popup blocker via javascript. I am looking for something similiar but for the cache setting, not the popup blocker.

Answer 1

Append something to the querystring that is unlikely to have been used before (a datestring, a random number).

That will make IE 6 request the page again, as far as IE is concerned, its another page.

So if you have http://somepage.com/dontcachethis.html you'd replace this with something like http://somepage.com/dontcachethis.html?please=23143425 where you asign please a random number.

Answer 2

Add the following to your web pages:

meta http-equiv="Pragma" content="no-cache"
meta http-equiv="Expires" content="0"

This forces the user's browser to reload the pages every time, regardless of the browser's cache settings.

Answer 3

I've not implemented this yet, but this is my plan:

• Write out a date onto the page that is on an attribute of some HTML element (this should be written server side...writing it with javascript will defeat the purpose)
• Using javascript, load in the date. If it is over a certain amount of time, I can assume they have not loaded a fresh copy of the page. If that is the case, continue on...

If I've detected that they have an old version of a page, I could do a couple things:

1. I could warn them of this problem. I could show them the setting that they need to change.
2. I could redirect them to the same page but add something onto the querystring so it looks like a different page to the browser. If I do this, I would add something in my javascript that knows about this potential redirect loop.