Disable cache for some images

Disable cache for some images

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I generate some images using a PHP lib.

Sometimes the browser does not load the new generated file.

How can I disable cache just for images created dynamically by me?

Note: I have to use same name for the created images over time.


A common and simple solution to this problem that feels like a hack but is fairly portable is to add a randomly generated query string to each request for the dynamic image.

So, for example -

<img src="image.png" />

Would become

<img src="image.png?dummy=8484744" />

Or

<img src="image.png?dummy=371662" />

From the point of view of the web-server the same file is accessed, but from the point of view of the browser no caching can be performed.

The random number generation can happen either on the server when serving the page (just make sure the page itself isn't cached...), or on the client (using JavaScript).

You will need to verify whether your web-server can cope with this trick.

Disable cache for some images, I generate some images using a PHP lib. Sometimes the browser does not load the new generated file. How can I disable cache just for images created  Windows 10 maintains a cache database with thumbnail images for every folder, document, video, and picture on your computer. This database is used to quickly display a preview of a file or to give


Browser caching strategies can be controlled by HTTP headers. Remember that they are just a hint, really. Since browsers are terribly inconsistent in this (and any other) field, you'll need several headers to get the desired effect on a range of browsers.

header ("Pragma-directive: no-cache");
header ("Cache-directive: no-cache");
header ("Cache-control: no-cache");
header ("Pragma: no-cache");
header ("Expires: 0");

How to prevent image from caching in javascript, List of © 2020 Ajay Matharu. Some rights reserved. Powered by Jekyll with  Press F12 to make the console appear, as shown in the image below. Now click on the three vertical dots in the upper right-hand corner and select Settings. In the next window, Under Preference tab Tick the option which says Disable cache (while DevTools is open) and doesn’t close DevTools. Disable Cache by installing Cache Killer Extension:


If you need to do it dynamically in the browser using javascript, here is an example...

<img id=graph alt="" 
  src="http://www.kitco.com/images/live/gold.gif" 
  />

<script language="javascript" type="text/javascript">
    var d = new Date(); 
    document.getElementById("graph").src = 
      "http://www.kitco.com/images/live/gold.gif?ver=" + 
       d.getTime();
</script>

How to prevent browser image caching?, instead of from the business object on the server. The following tutorial will help you to disable caching for a particular website in Google Chrome. Steps to Temporarily Disable Caching For A Specific Website in Chrome. 1. First of all, open the website for which you want to disable caching, with Google Chrome. Press F12 to open the console. 2. Now click on ‘Settings’ from the drop-down menu.


Solution 1 is not great. It does work, but adding hacky random or timestamped query strings to the end of your image files will make the browser re-download and cache every version of every image, every time a page is loaded, regardless of weather the image has changed or not on the server.

Solution 2 is useless. Adding nocache headers to an image file is not only very difficult to implement, but it's completely impractical because it requires you to predict when it will be needed in advance, the first time you load any image which you think might change at some point in the future.

Enter Etags...

The absolute best way I've found to solve this is to use ETAGS inside a .htaccess file in your images directory. The following tells Apache to send a unique hash to the browser in the image file headers. This hash only ever changes when time the image file is modified and this change triggers the browser to reload the image the next time it is requested.

<FilesMatch "\.(jpg|jpeg)$">
FileETag MTime Size
</FilesMatch>

How to set HTTP headers (for cache-control)?, a response, but must first submit a validation request to an origin server. (with the above solution, it disables the cache for that image completely) So, to serve cached image from browser UNTIL there is a change in the image file use: echo "<img src='/images/mychart.png?hash=" . filemtime('mychart.png') . "'>";


I checked all the answers and the best one seemed to be (which isn't):

<img src="image.png?cache=none">

at first.

However, if you add cache=none parameter (which is static "none" word), it doesn't effect anything, browser still loads from cache.

Solution to this problem was:

<img src="image.png?nocache=<?php echo time(); ?>">

where you basically add unix timestamp to make the parameter dynamic and no cache, it worked.

However, my problem was a little different: I was loading on the fly generated php chart image, and controlling the page with $_GET parameters. I wanted the image to be read from cache when the URL GET parameter stays the same, and do not cache when the GET parameters change.

To solve this problem, I needed to hash $_GET but since it is array here is the solution:

$chart_hash = md5(implode('-', $_GET));
echo "<img src='/images/mychart.png?hash=$chart_hash'>";

Edit:

Although the above solution works just fine, sometimes you want to serve the cached version UNTIL the file is changed. (with the above solution, it disables the cache for that image completely) So, to serve cached image from browser UNTIL there is a change in the image file use:

echo "<img src='/images/mychart.png?hash=" . filemtime('mychart.png') . "'>";

filemtime() gets file modification time.

Caching of GET requests, There are several kinds of caches: these can be grouped into two main request containing a resource like HTML documents, images or files. The cache consists of items that Microsoft Edge finds and saves while you surf the web. Websites can and do change their data regularly, so there's a chance that what's in your cache is outdated. When Microsoft Edge loads that outdated information, you won't see the most up-to-date information from the websites you visit.


What is Cache-Control and How HTTP Cache Headers Work, Akamai caching rules determine what gets cached and what doesn't. Use the default rule when not applying other, more specific rules. For dynamic content, such as images that change frequently based on your site visitors' actions or  This can apply to all of our css, js, and images files (max-age=31536000); after we change something, the browser will just request a new file with a new hash sum, which it will then cache. no-cache


HTTP caching, Viewing a site in Incognito mode should give you a clean slate void of any cached items and images. If you're in a session, then it will reset it for you too. So you  Jetpack Photon is an image accelerator you can use to speed up the load times of your images comes from Jetpack.Photon is a great, easier and free option to speed up your Website load times by using super fast servers.


Caching rules, Efficiently using the browser cache can improve end user response times and reduce bandwidth utilization. this includes the static images and includes forcing the browser to request the content on To enable/disable caching of SSL content: Some web developers will add random numbers to part of the query string to