Force Browser to Clear Cache

Question

Is there a way I can put some code on my page so when someone visits a site, it clears the browser cache, so they can view the changes?

Languages used: ASP.NET, VB.NET, and of course HTML, CSS, and jQuery.

Accepted Answer

If this is about .css and .js changes, one way is to to "cache busting" is by appending something like "_versionNo" to the file name for each release. For example:

script_1.0.css // This is the URL for release 1.0
script_1.1.css // This is the URL for release 1.1
script_1.2.css // etc.

Or alternatively do it after the file name:

script.css?v=1.0 // This is the URL for release 1.0
script.css?v=1.1 // This is the URL for release 1.1
script.css?v=1.2 // etc.

You can check out this link to see how it could work.

Answer 2

Look into the cache-control and the expires META Tag.

<META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE">
<META HTTP-EQUIV="EXPIRES" CONTENT="Mon, 22 Jul 2002 11:12:01 GMT">

Another common practices is to append constantly-changing strings to the end of the requested files. For instance:

<script type="text/javascript" src="main.js?v=12392823"></script>

Answer 3

Must Read

Update 2012

This is an old question but I think it needs a more up to date answer because now there is a way to have more control of website caching.

In Offline Web Applications (which is really any HTML5 website) applicationCache.swapCache() can be used to update the cached version of your website without the need for manually reloading the page.

This is a code example from the Beginner's Guide to Using the Application Cache on HTML5 Rocks explaining how to update users to the newest version of your site:

// Check if a new cache is available on page load.
window.addEventListener('load', function(e) {

  window.applicationCache.addEventListener('updateready', function(e) {
    if (window.applicationCache.status == window.applicationCache.UPDATEREADY) {
      // Browser downloaded a new app cache.
      // Swap it in and reload the page to get the new hotness.
      window.applicationCache.swapCache();
      if (confirm('A new version of this site is available. Load it?')) {
        window.location.reload();
      }
    } else {
      // Manifest didn't changed. Nothing new to server.
    }
  }, false);

}, false);

See also Using the application cache on Mozilla Developer Network for more info.

Force Browser to Clear Cache

20 Answers

Must Read

Update 2012

Maya Lin-Takahashi