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

For my site I have the following htaccess rules:

# BEGIN Gzip
<IfModule mod_deflate.c>
AddOutputFilterByType DEFLATE text/text text/html text/plain text/xml text/css application/x-javascript application/javascript
</IfModule>
# END Gzip


# BEGIN EXPIRES
<IfModule mod_expires.c>
ExpiresActive On
ExpiresDefault "access plus 10 days"
ExpiresByType text/css "access plus 1 month"
ExpiresByType text/plain "access plus 1 month"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType application/x-javascript "access plus 1 month"
ExpiresByType application/javascript "access plus 1 month"
ExpiresByType application/x-icon "access plus 1 year"
</IfModule>
# END EXPIRES

I've just updated my site and it looked all screwy until I cleared my cache. How can I force the client's browser to clear the cache after an update so that the user can see the changes?

191420 次浏览
小开
最佳答案

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.

小开

I got your problem...

Although we can clear client browser cache completely but you can add some code to your application so that your recent changes reflect to client browser.

In your <head>:

<meta http-equiv="Cache-Control" content="no-cache" />
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="0" />
小开

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.

小开

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.

小开

You can set "access plus 1 seconds" and that way it will refresh the next time the user enters the site. Keep the setting for one month.

小开

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.

小开

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

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

versioning by date.

小开

Change the name of the .CSS file Load the page and then change the file again in the original name it works for me.

小开

In my case, I change a lot an specific JS file and I need it to be in its last version in all browsers where is being used.

I do not have a specific version number for this file, so I simply hash the current date and time (hour and minute) and pass it as the version number:

<script src="/js/panel/app.js?v=\{\{ substr(md5(date("Y-m-d_Hi")),10,18) }}"></script>

I need it to be loaded every minute, but you can decide when it should be reloaded.

小开

Now the following wont help you with files that are already cached, but moving forward, you can use the following to easily force a request to get something new, without changing the actual filename.

# Rewrite all requests for JS and CSS files to files of the same name, without
# any numbers in them. This lets the JS and CSS be force out of cache easily
# by putting a number at the end of the filename
# e.g. a request for static/js/site-52.js will get the file static/js/site.js instead.
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteRule ^static/(js|css)/([a-z]+)-([0-9]+)\.(js|css)$ /site/$1/$2.$4 [R=302,NC,L]
</IfModule>

Of course, the higher up in your folder structure you do this type of approach, the more you kick things out of cache with a simple change.

So for example, if you store the entire css and javascript of your site in one main folder

/assets/js
/assets/css
/assets/...

Then you can could start referencing it as "assets-XXX" in your html, and use a rule like so to kick all assets content out of cache.

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteRule ^assets-([a-z0-9]+)/(.*) /$2 [R=302,NC,L]
</IfModule>

Note that if you do go with this, after you have it working, change the 302 to a 301, and then caching will kick in. When it's a 302 it wont cache at the browser level because it's a temporary redirect. If you do it this way, then you could bump up the expiry default time to 30 days for all assets, since you can easily kick things out of cache by simply changing the folder name in the login page.

<IfModule mod_expires.c>
ExpiresActive on
ExpiresDefault A2592000
</IfModule>
小开

This worked for me.

look for this:

    DirectoryIndex index.php

replace with this:

    DirectoryIndex something.php index.php

Upload and refresh page. You will get a page error.

just change it back to:

    DirectoryIndex index.php

reupload and refresh page again.
I checked this on all of my devices and, it worked.

小开

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

小开

Adding 'random' numbers to URLs seems inelegant and expensive to me. It also spoils the URL of the pages, which can look like index.html?t=1614333283241 and btw users will have dozens of URLs cached for only one use.
I think this kind of things is what .htaccess files are meant to solve at the server side, between your functional code an the users.

I copy/paste this code from here that allows filtering by file extension to force the browser not to cache them. If you want to return to normal behavior, just delete or comment it.

Create or edit an .htaccess file on every folder you want to prevent caching, then paste this code changing file extensions to your needs, or even to match one individual file.
If the file already exists on your host be cautious modifying what's in it.
(kudos to the link)

# DISABLE CACHING
<IfModule mod_headers.c>
Header set Cache-Control "no-cache, no-store, must-revalidate"
Header set Pragma "no-cache"
Header set Expires 0
</IfModule>


<FilesMatch "\.(css|flv|gif|htm|html|ico|jpe|jpeg|jpg|js|mp3|mp4|png|pdf|swf|txt)$">
<IfModule mod_expires.c>
ExpiresActive Off
</IfModule>
<IfModule mod_headers.c>
FileETag None
Header unset ETag
Header unset Pragma
Header unset Cache-Control
Header unset Last-Modified
Header set Pragma "no-cache"
Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"
Header set Expires "jue, 1 Jan 1970 00:00:00 GMT"
</IfModule>
</FilesMatch>

提交答案