As suggested by an answer on SO, I'm trying using a version number on my JS and CSS files so that the browser will only make a request when the JS or CSS version number is changed in my PHP file. To facilitate this, I have a rewrite in my httpd.conf which transforms a requested file like myscript--20140904.js to myscript.js. Since I'm doing things this way, I want the browser to cache the file for a long time, since it will see a request for a "different" file when that version number is updated.

According to an answer on Webmasters.SE, I can use FilesMatch along with Header set Cache-Control to only cache the CSS/JS files with the version number on them.

And according to an answer on SO, only Cache-Control is necessary, since it takes precedence over Expires anyway.

But this is not working. The Cache-Control header field is missing from the response.

Here's my Apache configuration:

RewriteEngine on
RewriteRule ^(.*)\-\-.+\.(css|js)$ $1.$2

<IfModule mod_headers.c>
    <FilesMatch "^(.*)\-\-.+\.(js|css)$">
        Header set Cache-Control "max-age=15552000"
        Header unset ETag
        Header unset Last-Modified

# <IfModule mod_expires.c>
#     <FilesMatch "\.(js|css)$">
#         ExpiresActive On
#         ExpiresByType text/javascript "access plus 6 months"
#         ExpiresByType text/css "access plus 6 months"
#     </FilesMatch>
# </IfModule>

Here's a request for one of the JS files:


GET [url]/common.js HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:31.0) Gecko/20100101 Firefox/31.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://localhost/[refererUrl]
Cookie: PHPSESSID=[cookie]
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache

HTTP/1.1 200 OK
Date: Thu, 04 Sep 2014 19:45:32 GMT
Server: Apache
Last-Modified: Wed, 03 Sep 2014 22:55:57 GMT
Etag: [etag]
Accept-Ranges: bytes
Content-Length: 5167
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: application/javascript
  • Have you tried it without using <IfModule mod_headers.c>, FilesMatch should be enough. – Simon Hayter Sep 5 '14 at 8:59
<FilesMatch "^(.*)\-\-.+\.(js|css)$">

FilesMatch takes a filename and matches against the file system, not the URL. The underlying file is still called "myscript.js", so this pattern should be something like: \.(js|css)$

(Aside... your example request appears to be for common.js - which wouldn't have matched your pattern anyway - shouldn't this be for common--20140904.js?)

  • Whoops, using common.js was a typo. I was picking them from a list of headers. The info otherwise was the same though. – AmadeusDrZaius Sep 5 '14 at 20:36
  • Are you saying I should be using something other than FilesMatch? I was matching the filename, not the url. – AmadeusDrZaius Sep 5 '14 at 20:37
  • No, I think FilesMatch should be OK. However, you weren't matching the filename, you were trying to match the URL. The regex ^(.*)\-\-.+\.(js|css)$ would only match a filename of the form common--20140904.js, but that is the URL. The filename is simply common.js, which the regex would not match. – MrWhite Sep 5 '14 at 21:16
  • Oh, I see now... Yes, you're totally right. Thanks! – AmadeusDrZaius Sep 5 '14 at 22:00

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