If you look at their response headers and translate that into aspx, they're doing: Response. AppendHeader "Cache-Control", "no-cache, no-store, must-revalidate" ; Response. It works, but it's somewhat ridiculous to take exactly that timestamp. Show 44 more comments. However, in practice, the cache can influence the back button, in very specific circumstances: Page must be delivered over HTTPS , otherwise, this cache-busting won't be reliable.
Totally useless. Sending the same header twice or in dozen parts. Some PHP snippets out there actually replace previous headers, resulting in only the last one being sent. Farzad Karimi 11 11 silver badges 26 26 bronze badges.
Kornel Kornel RamanGhai Disabling cache generally hurts performance and all 3 options you've mentioned disable caching. It doesn't hurt first load by a new user aside from the proxy issue , but then subsequent navigation may be a lot slower. Why not send Cache-Control: no-cache since no-cache already implies must-revalidate? Pacerier the relationship of no-cache with must-revalidate is true for cache, but back history is not a cache.
Browsers special-case explicit must-revalidate to control history behavior. In Chrome v In FireFox v In Safari v5. Ritesh 7, 2 2 gold badges 36 36 silver badges 42 42 bronze badges. Pacerier Pacerier I know this was posted a couple years back but it was an interesting read. This problem has been driving me crazy for a few months now, body seems to really know how to deal with cache control. I've tried using the. It's mainly safari where the problem arrises most.
Add a comment. Royi Namir k gold badges silver badges bronze badges. Joseph Connolly Joseph Connolly 8 8 silver badges 20 20 bronze badges. For web. For who is may wondering what web. NET web application. It is an XML document that resides in the root directory.
Community Bot 1 1 1 silver badge. Chris Vasselli Chris Vasselli This works for IE8's back button!! Combined with the headers suggested by BarlusC, plus a JS snippet that calls window. CoreDumpError, oh you should not assume JavaScript is enabled.
Pacerier At the time I wrote the answer in , this worked on what were then the latest versions of both Safari and Opera, with our server identifying itself as an HTTP 1. Unfortunately, I don't have any way to easily test this anymore, so I can't say anything definitive about the latest versions of these browsers. What were the browser versions you tested with? Show 1 more comment. NET we added these using the following snippet: Response.
ClearHeaders ; Response. Cache-Control: no-cache and Cache-Control: private clash - you should never get both together: the former tells browsers and proxies not to cache at all, the latter tells proxies not to cache but lets browsers hold their own private copy.
I'm not sure which setting the browser will follow, but it's unlikely to be consistent between browsers and versions. Do not use pre-check and post-check. I had to follow this: stackoverflow. Dave Cheney Dave Cheney 5, 2 2 gold badges 17 17 silver badges 24 24 bronze badges. This is a good example of why you need to go beyond the specs. If the specs were always crystal clear, there wouldn't be much point for sites like StackOverflow. However, for historical reasons and because I have tested it myself , I will include my original answer below: I tried the 'accepted' answer for PHP, which did not work for me.
So, when setting the Cache-Control , for example if one does not want to put all the arguments in one header function call, he must do something like this: header 'Cache-Control: this' ; header 'Cache-Control: and, this', false ; See more complete documentation here. Steven Oxley Steven Oxley 6, 6 6 gold badges 38 38 silver badges 54 54 bronze badges.
This is full of myths. Expires accepts only single value. More than one will cause this header to be ignored. Oddthinking, looks like stackoverflow. Pacerier yes, as I say in the disclaimer, use BalusC's answer. Edson Medina Edson Medina 8, 3 3 gold badges 39 39 silver badges 49 49 bronze badges.
For ASP. Append "Cache-Control", "no-cache, no-store, must-revalidate" ; httpContext. Append "Pragma", "no-cache" ; httpContext. Append "Expires", "0" ; return Task. UseStaticFiles ;. I would suggest to use constants from Microsoft. Dustman Dustman 4, 10 10 gold badges 31 31 silver badges 40 40 bronze badges. Chris Dail Chris Dail The spec indicates that the response must not be reused without revalidation. It is the Cache-Control:no-store which is the official method to indicate that the response not even be stored in a cache in the first place.
Setting the modified http header to some date in usually does the trick. Anders Sandvig Anders Sandvig 20k 16 16 gold badges 57 57 silver badges 72 72 bronze badges. Setting a long-ago Last-Modified has no impact on caching, other than letting a cached response be used longer due to heuristic revalidation.
Grey Panther Grey Panther This is obviously wrong. Second calls to header for Expires, Cache-control and Pragma completely overwrite previously set values. JulienPalard the answer has been edited after I made my comment. It still doesn't make much sense. Do not send multiple Cache-Control headers if you want to work in IE prior to 9. Don't EVER send pre-check or post-check. Albert Albert 71 1 1 silver badge 1 1 bronze badge.
My mozilla Thank you. This way works with IIS7: Response. NoCache ; Response. AppendHeader "Pragma", "no-cache" ; Response. AppendHeader "Expires", "-1" ; The first line sets Cache-control to no-cache , and the second line adds the other attributes no-store, must-revalidate. This works for me: Response. SetNoStore ; Response.
SetRevalidation HttpCacheRevalidation. AllCaches ; — Vilx-. For example, clearing a browser cache typically means you'll have to log into all your favorite websites all over again, and you'll lose any special customizations or personalization you had there, including the contents of shopping carts or baskets. But if you're experiencing problems with your Mac, PC, or mobile device, clearing the cache is worth it. For you. World globe An icon of the world globe, indicating different international options.
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Dave Johnson. A cache is a special storage space for temporary files that makes a device, browser, or app run faster and more efficiently. After opening an app or website for the first time, a cache stashes files, images, and other pertinent data on your device.
If this is about. For example:. You can check out this link to see how it could work. Another common practices is to append constantly-changing strings to the end of the requested files. For instance:. 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. See also Using the application cache on Mozilla Developer Network for more info.
Things change quickly on the Web. This question was asked in and in I posted an update about a new way to handle the problem described in the question. Another 4 years passed and now it seems that it is already deprecated.
Thanks to cgaldiolo for pointing it out in the comments. This feature is in the process of being removed from the Web platform. This is a long process that takes many years. Using any of the offline Web application features at this time is highly discouraged. Use service workers instead. Deprecated This feature has been removed from the Web standards. Though some browsers may still support it, it is in the process of being dropped. Do not use it in old or new projects.
Pages or Web apps using it may break at any time. See also Bug - Add a deprecation notice for AppCache if service worker fetch interception is enabled.
Not as such. One method is to send the appropriate headers when delivering content to force the browser to reload:. Making sure a web page is not cached, across all browsers. NET specific examples. Another, less clean but sometimes only way if you can't control the headers on server side, is adding a random GET parameter to the resource that is being called:. For static resources right caching would be to use query parameters with value of each deployment or file version. This will have effect of clearing cache after each deployment.
In cache. It is important now that it works in my case Apache just by updating each time the "version" comment. It is also an option to name files with "? Changing just version 1. Now you just change files and in manifest you have to update version comment. Now visiting index. The parts of solution aren't mine but I've found them through internet and put together so that it works. I had a case where I would take photos of clients online and would need to update the div if a photo is changed.
Browser was still showing the old photo. So I used the hack of calling a random GET variable, which would be unique every time.
Here it is if it could help anybody. EDIT As pointed out by others, following is much more efficient solution since it will reload images only when they are changed, identifying this change by the file size:. A lot of answers are missing the point - most developers are well aware that turning off the cache is inefficient. However, there are many common circumstances where efficiency is unimportant and default cache behavior is badly broken.
These include nested, iterative script testing the big one! None of the solutions given here are adequate to address such common scenarios. Most web browsers are far too aggressive caching and provide no sensible means to avoid these problems.
By adding a unique number after? Alternatively, you can append hash or string version of the current time or Epoch after?
Not sure if that might really help you but that's how caching should work on any browser. When the browser request a file, it should always send a request to the server unless there is a "offline" mode. The server will read some parameters like date modified or etags. If the etag doesn't validate on server side or the modified date is below the current modified date, the server should return the new content with the new modified date or etags or both.
If there is no caching data sent to the browser, I guess the behavior is undetermined, the browser may or may not cache file that don't tell how they are cached.
If you set caching parameters in the response it will cache your files correctly and the server then may choose to return a error, or the new content. This is how it should be done. Using random params or version number in urls is more like a hack than anything. After reading I saw that there is also a expire date. If you have problem, it might be that you have a expire date set up. In other words, when the browser will cache your file, since it has a expiry date, it shouldn't have to request it again before that date.
In other words, it will never ask the file to the server and will never receive a not modified. It will simply use the cache until the expiry date is reached or cache is cleared. So that is my guess, you have some sort of expiry date and you should use last-modified etags or a mix of it all and make sure that there is no expire date. If people tends to refresh a lot and the file doesn't get changed a lot, then it might be wise to set a big expiry date.
This function is called in all of my pages, so when loading it checks if the localStorage's version value is lower than the current version and does a. I opted for this solution for its simplicity, because only mantaining a single file "versio. The queryString method is hard to implement and is also cached if you change from v1. In addition to setting Cache-control: no-cache, you should also set the Expires header to -1 if you would like the local copy to be refreshed each time some versions of IE seem to require this.
There is one trick that can be used. The browser interprets the whole string as the file path even though what comes after the "? Force browsers to clear cache or reload correct data? I have tried most of the solutions described in stackoverflow, some work, but after a little while, it does cache eventually and display the previous loaded script or file.
Is there another way that would clear the cache css, js, etc and actually work on all browsers? I found so far that specific resources can be reloaded individually if you change the date and time on your files on the server. Instead of clearing cache on my browsers, I realized that "touching" the server files cached will actually change the date and time of the source file cached on the server Tested on Edge, Chrome and Firefox and most browsers will automatically download the most current fresh copy of whats on your server code, graphics any multimedia too.
I suggest you just copy the most current scripts on the server and "do the touch thing" solution before your program runs, so it will change the date of all your problem files to a most current date and time, then it downloads a fresh copy to your browser:. It took me some time to resolve this issue as many browsers act differently to different commands, but they all check time of files and compare to your downloaded copy in your browser, if different date and time, will do the refresh , If you can't go the supposed right way, there is always another usable and better solution to it.
Best Regards and happy camping. By the way touch ; or alternatives work in many programming languages inclusive in javascript bash sh php and you can include or call them in html. It will automatically force cache refresh if the content has been updated and it solves this issue completely and reliably.
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