Make Browsers Cache Static Files With mod_expires On Apache2

mod_expires

Enabling mod_expires

  a2enmod expires

Configuring mod_expires

If you have multiple file types that should expire after the same time after they have been accessed (let's say in one week), 
you can use a combination of the FilesMatch and the ExpiresDefault directives, e.g. as follows:

  <IfModule mod_expires.c>
            <FilesMatch "\.(jpe?g|png|gif|js|css)$">
                        ExpiresActive On
                        ExpiresDefault "access plus 1 week"
            </FilesMatch>
  </IfModule>

This would tell browsers to cache .jpg, .jpeg, .png, .gif, .js, and .css files for one week.

Instead of using FilesMatch and ExpiresDefault directives, you could also use the ExpiresByType directice 
and set an Expires header (plus the max-age directive of the Cache-Control HTTP header) individually for each file type, 
e.g. as follows:

  <IfModule mod_expires.c>
            ExpiresActive on

            ExpiresByType image/jpg "access plus 60 days"
            ExpiresByType image/png "access plus 60 days"
            ExpiresByType image/gif "access plus 60 days"
            ExpiresByType image/jpeg "access plus 60 days"

            ExpiresByType text/css "access plus 1 days"

            ExpiresByType image/x-icon "access plus 1 month"

            ExpiresByType application/pdf "access plus 1 month"
            ExpiresByType audio/x-wav "access plus 1 month"
            ExpiresByType audio/mpeg "access plus 1 month"
            ExpiresByType video/mpeg "access plus 1 month"
            ExpiresByType video/mp4 "access plus 1 month"
            ExpiresByType video/quicktime "access plus 1 month"
            ExpiresByType video/x-ms-wmv "access plus 1 month"
            ExpiresByType application/x-shockwave-flash "access 1 month"

            ExpiresByType text/javascript "access plus 1 week"
            ExpiresByType application/x-javascript "access plus 1 week"
            ExpiresByType application/javascript "access plus 1 week"
  </IfModule>

You might have noticed that I've set three ExpiresByType directives for Javascript files - that is because Javascript files 
might have different file types on each server. If you set just one directive for text/javascript, but the server recognizes 
the Javascript file as application/javascript, then it will not be covered by your configuration, and no cache headers will be set.