htaccess - How to force the client's browser to clear the cache?

Question

For my site I have the following htaccess rules:

# BEGIN Gzip

AddOutputFilterByType DEFLATE text/text text/html text/plain tex         


        

Answer 1

You can force browsers to cache something, but

You can't force browsers to clear their cache.

Thus the only (AMAIK) way is to use a new URL for your resources. Something like versioning.

Answer 2

As other answers have said, changing the URL is a good cache busting technique, however it is alot of work to go through a bigger site, change all the URLs and also move the files.

A similar technique is to just add a version parameter to the URL string which is either a random string / number or a version number, and target the changed files only.

For instance if you change your sites CSS and it looks wonky until you do a force refresh, simply add ?ver=1.1 to the CSS import at the head of the file. This to the browser is a different file, but you only need to change the import, not the actual location or name of the file.

e.g:

<link href="assets/css/style.css" rel="stylesheet" type="text/css" />

becomes

<link href="assets/css/style.css?ver=1.1" rel="stylesheet" type="text/css" />

Works great for javascript files also.

Answer 3

The most straight forward is to add filetime to the request. eg

myfile.txt?2014-10-30-13:12:33

versioning by date.

Answer 4

You can not force the browsers to clear the cache.

Your .html file seems to be re-loaded sooner as it expires after 10 days. What you have to do is to update your .html file and move all your files to a new folder such as version-2/ or append a version identifier to each file such as mypicture-2.jpg. Then you reference these new files in your .html file and the browser will load them again because the location changed.

Answer 5

You can tell the browser never cache your site by pasting following code in the header

<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="0" />

And to prevent js, css cache, you could use tool to minify and obfuscate the scripts which should generate a random file name every time. That would force the browser to reload them from server too.

Hopefully, that helps.

Answer 6

Use the mod rewrite with R=301 - where you use a incremental version number:

To achieve > css/ver/file.css => css/file.css?v=ver

RewriteRule ^css/([0-9]+)/file.css$ css/file.css?v=$1 [R=301,L,QSA]

so example, css/10/file.css => css/file.css?v=10

Same can be applied to js/ files. Increment ver to force update, 301 forces re-cache

I have tested this across Chrome, Firefox, Opera etc

PS: the ?v=ver is just for readability, this does not cause the refresh