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I'm trying to prevent 2 JavaScript files from being cached by the browser.

I've tryed to use <META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE"> without success. Here's my <head> element code:

    <head>

<meta charset="UTF-8">
<meta http-equiv="Cache-control" content="NO-CACHE">

<link type='text/css' href='/files/theme/popup_basic.css' rel='stylesheet' media='screen' />

<!-- JavaScript Start -->
<script type="text/javascript" src="/files/theme/gohome.js"></script>
<script type="text/javascript" src="http://192.168.0.149/redirect.js"></script>
<!-- JavaScript End -->

</head>

From my understating, this should work. But the redirect.js file keeps being cached!

Anyone know what I'm doing wrong?

Ryan Fitzgerald
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    Why would you want to prevent caching of the file? If you're generating the HTML on the server, you could append a GUID to the src attribute, resulting in a unique "file" like this: `` – Bernhard Hofmann Mar 07 '13 at 17:30
  • Because this file is a redirect and it only needs to be redirected when the server is online. When it is offline, the user will stay at that page. – Ryan Fitzgerald Mar 07 '13 at 17:37

1 Answers1

15

The <meta http-equiv="Cache-control" content="NO-CACHE">, the directive CACHE-CONTROL:NO-CACHE indicates cached information should not be used and instead requests should be forwarded to the origin server.

In order to prevent cache on every request, you may need to add some random string in url. The example below is use javascript to dynamic create a script tag and adding random number in the url, then append it. 

<script language="JavaScript">
 var s=document.getElementsByTagName('script')[0];
 var sc=document.createElement('script');
 sc.type='text/javascript';
 sc.async=true;
 sc.src='http://192.168.0.149/redirect.js?v' + Math.random(); 
 s.parentNode.insertBefore(sc,s);
</script>

If just want to prevent 1 time only, just append some string to the src.

<script src="http://192.168.0.149/redirect.js?12345678"></script>
Derek
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  • You don't have to generate a random number, it can be a statically typed number using pure HTML. (See my answer). – Jace Cotton Mar 07 '13 at 17:37
  • I'm considering the case that want to prevent the file cached on every request. – Derek Mar 07 '13 at 17:42
  • Well I've tried static numbers before and they don't work. That's why I normally use PHP to use the date. Random numbers is really what you need. (I'm guessing.) – Ryan Fitzgerald Mar 07 '13 at 17:42
  • So, you know how to use date.Random numbers to add random string to the src, then what are you seeking? The case above, I'm assuming you are not going to use any server side language. – Derek Mar 07 '13 at 17:46
  • Well. I can't use a server side language. That's why I was forced into JS. I just didn't know how to do this! This works great. And was exactly what I was looking for. Thanks so much! – Ryan Fitzgerald Mar 07 '13 at 17:48
  • OK, you are welcome. It is better to show the constraint in the question next time :) – Derek Mar 07 '13 at 17:51
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    @JaceCotton WHere is your answer you're referring to? – Stealth Rabbi Apr 11 '18 at 19:41