Question:

JavaScript provides straightforward methods for detecting things like browser version and platform, and a few options such as whether the client will accept cookies. But is there a way to detect some of the more subtle settings, such as caching options? I want to warn users who have their browser set to never check for new page content that this setting will cause them problems.

Answer:

While you can’t use JavaScript to determine most user browser settings, like client-side caching, this shouldn’t prevent you from solving the problem you’ve run up against. In fact, to control how browsers cache your pages you don’t need to use JavaScript at all. The HTML tag is all you need. Just place the tag within the document’s section it will let the browser know how to handle caching your page. You can either specify that a page should not be cached at all using:

or specify a date after which the page should be removed from the cache:

If you really don’t want a browser to cache your page you can use both tags together and set the “expires” date to a date that has already passed.