Advice on mimetypes to include in Apache mod_expires

I used this excellent post Website image caching with Apache to define my header expires. And I have looked at numerous other examples, and they all pretty much outline the same; enable for images and css, disable for php, python etc.

But I am a bit ambiguous about JavaScripts and HTML. Can I add header expire for those as well? Without compromising the live content of the site? I am running Simple Machines forum.

By top eight mimetypes by use look like this, so there is something to gain:

php  46.5 %
png  22.9 %
js   6.5 %
html 5.9 %
gif  5.8 %
css  4.8 %
jpg  4.7 %
jpeg 2.6 %

Solution

So, I dug around the Simple Machines forums and was recommended to enable it for JavaScript but not for HTML as the pretty URL function makes some dynamic pages apear as HTML, e.g. index.php/board,1.0.html

Have been testing it for a couple of days now and found no issues so far, and it has really reduced the daily download.