i was wondering - when using jQuery (or any other javascript include) in my web,
does the browser cache it after the first download for all all pages (i assume yes) or will it download it every time?
2nd, when the user quits the browser and starts it again (for loading my website), will the jquery js file still be cached or will it completely download again?
thx
This depends on the browser and on how your server is set up. Have a look at the headers sent by the server along with the file (you can use a tool like Firebug to look at the headers). A good idea is to use the jQuery file hosted by google, since many other sites (including stackoverflow) use the same file. Then the browser can cache that file and never download it from your server. This page has a list of files hosted by google, and this page explains how to properly set your server up to (tell your browser to) cache files.
1: Yes, the browser caches all jscript/css includes
2: If the user does not clear his/her cache. Yes it will still be in the cache of the browser, even after closing and reopening it.
If your webserver serves jquery.js using a proper expires header, then yes, the browser will cache it.
http://developer.yahoo.com/performance/rules.html#expires
Yes the scripts will get cached between page views, along with the CSS files and images.
Yes as well, in general. The cache is normally maintained between browser restarts.
It will typically not be downloaded again, but unless your server explicitly tells the browser to cache it for a while, then it will send a request on each page load asking "was jquery.js updated?" which is almost as slow as just downloading it again.
You can test how it works on your site with Google's Page Speed or Yahoo's YSlow.
Related
I have a ReactJS app hosted in S3 and using Cloudflare as DNS & CDN.
I have a huge issue, a lot of visitors have old version of the application stored in their browser cache (index.html only). I have configured advanced cache control in the newest version, but it cannot be accessed because older version is shown instead.
Static file (CSS, JS) versioning is done using create-react-app, but I have discovered that index.html file is the only cached one.
What should I do now?
How to purge visitors cache now?
PS: I have purged Cloudflare cache already and setup rule to bypass cache.
Unfortunately there is no such solution for this.
The only way is to wait until users cache will empty (expire).
It is technicaly impossible to clear users cache from external resource (JS script etc.), due to security reasons.
Also if it will be possible, there is no way how to tell users to download latest JS (including cache purging code), because they have old version of index.html (including link to those .js files).
You are stack and the only option is to wait.
A better approach would be, whenever your build changes, change the JS link so that the browser downloads the new version from the server, no matter the user's or the server's caching policy.
For example, the way Stack Exchange does it is, whenever the build changes, the HTML goes from something like:
<script src="https://cdn.sstatic.net/Js/stub.en.js?v=1bac371ac78f"></script>
to
<script src="https://cdn.sstatic.net/Js/stub.en.js?v=f83b2f654"></script>
Whenever there's a new build, you can randomize the parameter in the query string in the HTML, and still only have the single (most recent) built .js on your server.
I have several web resources that are displayed on forms in Microsoft Dynamics. The web resources are html files that include JavaScript/CSS files. When I update the JavaScript files, I am seeing that the latest changes are not getting pulled to end user computers on their next use of the form. I believe this is because the previous version of the web resource has been cached on their machine.
According to this SO question, the solution would be to add a version to the script tag. However, according to the comments on the question, this solution does not work on Chrome and is considered a hack. I have also read here that Dynamics should automatically handle caching when web resources are updated, but does not do so reliably (which is my experience).
How can I force end user computers to get the latest version of my code on their next use of the form when I push out updates?
If you are only changing the files for development (ie. Once they are finished they won't change), then most browsers will allow you to disable the cache. In Chrome, this can be done as long as developer tools are open and you click the "disable cache" button in the network tab.
If they are going to change for the client with each request, then you can generate a random ID to be sent with the file (eg example.com/script.js?182hdh2). To allow this, just put some js in your html file (not in an external script) to import all the other files.
Is it possible to force caching of certain Javascript Library files (ie react.min.js, etc.) when navigating between pages of a website that isn't a SPA?
Trying to look at the feasibility of a more componentized structure while not going full on SPA. The website I'm working on oftentimes has people visit a single page and then leave, but in cases where they do stick around, I don't want to have to have them reload each and every library on page load.
Background You Should Understand
There are literally thousands of articles on the web about this topic but here is a very good summary from Make Us Of's Everything You Need to Know About the Browser Cache.
The browser cache is a temporary storage location on your computer for files downloaded by your browser to display websites. Files that are cached locally include any documents that make up a website, such as html files, CSS style sheets, JavaScript scripts, as well as graphic images and other multimedia content.
When you revisit a website, the browser checks which content was updated in the meantime and only downloads updated files or what is not already stored in the cache. This reduces bandwidth usage on both the user and server side and allows the page to load faster. Hence, the cache is especially useful when you have a slow or limited Internet connection.
TL;DR
I don't know if your really looking for a way to force the browser to cache your files or if you just misunderstood how the cache works. In general the browser the visitor is using is the one that makes that decision and handles everything for you. If it sees that a resource is needed that was already accessed in the past it wont request it again, it'll just use its cache. So no, your libraries will not get re-loaded over and over. Just once.
Now if you really do need to force the browser to cache your files take a look at the answer(s) to Caching a jquery ajax response in JavaScript/browser. That should get you on a good path to a solution.
I had problem that i added custom java script its included but when i changes its contents it doesn't effect. it runs older java script file. since i cleared cache. i deleted every folder of /var/ also. but still it runs older java script code. while i see it in uploaded file also it shows updated code but using URL of that java script in browser it shows old code.
I flushed magento cache storage. flushed cache of css/javascript also.
In case if any guy have solution let me know.
Thanks in advance.
EDITED
Same problem with css also. Changes doen't reflect. cleared cache a lot of times from back-end as well as cleared var folder also.
Your server probably have header information asking browsers to cache static files like JS/CSS. It is likely that your browser is still caching the old CSS files. One way to check if it is indeed the browser and not say accidentally editing the wrong CSS file is by enabling and disabling (only go one way to check) the CSS file merge. By doing so you are forcing the browser to fetch for a whole new file - essentially bypassing caching.
You may also want to take a look at our CSS/JS Versioning extension which includes automatic refresh of the file name hash based on CSS/JS file timestamps (sensitive to editing and changes) http://extensions.activo.com/css-and-javascript-versioning.html
Have you cleared your local browser cache on your workstation?
Often, CSS and JavaScript can stick mightily and no matter now much you flush Magento caching on the server, the workstation browser never requests and downloads the new script. These are static files, a change in file date doesn't trigger browser reload, only complete removal from the browser cache does.
Usually CTL-F5 about three times will do it, otherwise you have to go into the web browser setups and flush browser cache there.
Also, if you're using JavaScript/CSS Merge, you need to click the button on the Cache Management page to Flush JavaScript/CSS Cache as well.
The only other place things can gum up is if you're running APC cache, you may need to flush it as well so the block caching for the head can refresh. This only matters if you changed the script and CSS file names, which you probably haven't, so it likely doesn't matter.
There's this website which has a javascript method in it that downloads a file. To call this method you have to set what language and serial number you're looking for and when that's done, the file is being generated according to the specified information you've just stated and then the file is being downloaded. Does anyone know how to specify this information, then send it and then download the file without going to this website?
Thanks in advance, Steve-O
If you use any tool that shows you what actual networking happens, you can discover the specific web requests that downloads the file. Chrome has those tools built in. The Firebug add-on adds those tools into Firefox. There are also apps that record all networking to/from the browser such as Fiddler which can be used to sleuth on the networking being done.
Of course, there may also be some authentication going on (a log-in, some cookies, etc...) that might be required, but all of that is visible with the right developer tools. Once you see exactly what is being sent over the wire, it's usually not hard to send that same request without a browser or without visiting that web page. If login credentials are required, that will still be required, but even that can be provided without a browser (e.g. from a server-side script).
JavaScript, as of the moment, can't download files. So how files gets downloaded? Well, the developer redirects the browser to a URL using
location.href = 'http://site.com/download.zip';
When the browser is redirected to this URL, it can't open the file, so it downloads it.
You need to determine that URL the browser redirects to. There are many ways to do that. One that comes to mind is the Fiddler app that records each HTTP request and thus can give you the URL.
My guess, however, is that the URL is generated on the fly. You need to study the JavaScript in this case and see the required mechanism to make the server generates the URL.