I want to leverage browser caching to increase page speed. I've done some research on this and it sounds like max-age and and last-modified are good choices, but I'm unclear on how to determine which files I should implement for it. In general, I'm confused on how to actually do this and what the code would look like in my htaccess. I guess I'm looking to get some more explicit help or to be shown some examples. Or maybe someone can direct me to a lesson/tutorial on this that a novice like me can understand, which I haven't had any luck finding. Any help from someone who knows more about max-age and last-modified and can help tell me how to do this would be greatly appreciated.
If you do anything with document.lastModified, you should be aware of a small problem.
That item is part of a group and some of the items in that group can be used to attack the server. The administrator could block just the problem items, but more often just blocks the entire group. This means that you get a null response for the value.
Internet Explorer uses that null as-is in the Date function and gets the CURRENT date and time. That makes it look like you updated the page within the last few seconds. That looks good but isn't true.
Netscape converts the null to numeric, gets a zero, uses that zero in the Date function, and gets January 1st, 1970, at the first midnight, and then applies the timezone offset. For me in the eastern U.S., the result is December 31, 1969, at 7:00pm.
WebTV processes similarly to Netscape, but applies the timezone offset earlier, gets a negative value, tries to pass that to the Date function, and blows up.
All other browsers that I've tested follow one of the above patterns. Make sure that you allow for "null" as a result.