Unexpected Caching of AJAX results in IE8

IE is notorious for its aggressive caching of Ajax responses. As you're using jQuery, you can set a global option:

$.ajaxSetup({
    cache: false
});

which will cause jQuery to add a random value to the request query string, thereby preventing IE from caching the response.

Note that if you have other Ajax calls going on where you do want caching, this will disable it for those too. In that case, switch to using the $.ajax() method and enable that option explicitly for the necessary requests.

See http://docs.jquery.com/Ajax/jQuery.ajaxSetup for more info.

As marr75 mentioned, GET's are cached.

There are a couple of ways to combat this. Aside from modifying the response header, you can also append a randomly generated query string variable to the end of the targeted URL. This way, IE will think it is a different URL each time it is requested.

There are multiple ways to do this (such as using Math.random(), a variation on the date, etc).

Here's one way you can do it:

var oDate = new Date();
var sURL = "/game/getpuzzleinfo?randomSeed=" + oDate.getMilliseconds();
$.get(sURL, null, function(data, status) {
    // your work
});

Gets are always cacheable. One strategy that may work is to edit the response header and tell the client to not cache the information or to expire the cache very soon.

If you are calling ashx page you can also disable caching on the server with the following code:

context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
context.Response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches); 

this is what i do for ajax calls:

var url = "/mypage.aspx";
// my other vars i want to add go here
url = url + "&sid=" + Math.random();
// make ajax call

it works pretty well for me.

NickFitz gives a good answer, but you'll need to turn the caching off in IE9 as well. In order to target just IE8 and IE9 you could do this;

<!--[if lte IE 9]>
<script>
    $.ajaxSetup({
        cache: false
    });
</script>
<![endif]-->

The answers here are very helpful for those who use jQuery or for some reason directly use the xmlHttpRequest object...

If you're using the auto-generated Microsoft service proxy its not as simple to solve.

The trick is to use Sys.Net.WebRequestManager.add_invokingRequest method in the event handler change the request url:

networkRequestEventArgs._webRequest._url = networkRequestEventArgs._webRequest._url + '&nocache=' + new Date().getMilliseconds(); 

I've blogged about this: http://yoavniran.wordpress.com/2010/04/27/ie-caching-ajax-results-how-to-fix/

Just wrote a blog on this exact issue only using ExtJS (http://thecodeabode.blogspot.com/2010/10/cache-busting-ajax-requests-in-ie.html )

The problem was as I was using a specific url rewriting format I couldn't use conventional query string params (?param=value), so I had write the cache busting parameter as a posted variable instead..... I would have thought that using POST variables are a bit safer that GET, simply because a lot of MVC frameworks use the pattern

protocol://host/controller/action/param1/param2

and so the mapping of variable name to value is lost, and params are simply stacked... so when using a GET cache buster parameter

i.e. protocol://host/controller/action/param1/param2/no_cache122300201

no_cache122300201 can be mistaken for a $param3 parameter which could have a default value

i.e.

public function action($param1, $param2, $param3 = "default value") { //..// }

no chance of that happening with POSTED cache busters

If you are using ASP.NET MVC, it is enough to add this line on top of the controller action:

[OutputCache(NoStore=true, Duration = 0, VaryByParam = "None")]
public ActionResult getSomething()
{

}

IE is within its rights to do this caching; to ensure the item isn't cached, the headers should be set accordingly.

If you are using ASP.NET MVC, you can write an ActionFilter; in OnResultExecuted, check filterContext.HttpContext.Request.IsAjaxRequest(). If so, set the response's expire header: filterContext.HttpContext.Response.Expires = -1;

As per http://www.dashbay.com/2011/05/internet-explorer-caches-ajax/:

Some people prefer to use the Cache - Control: no - cache header instead of expires. Here’s the difference: Cache-Control:no-cache – absolutely NO caching Expires:-1 – the browser “usually” contacts the Web server for updates to that page via a conditional If-Modified-Since request. However, the page remains in the disk cache and is used in appropriate situations without contacting the remote Web server, such as when the BACK and FORWARD buttons are used to access the navigation history or when the browser is in offline mode.