Problem:
Chrome caches too much data, so when i create entries like Post and Comment in my db, its isn't loaded, but all the existing entries are being displayed.
Chrome refuses to run through my script, and just displays it from cache, and therefor not showing the new entry.
I can solve this problem partly by using
Location.reload(true);
But when i create a post i route back to the overview of all posts, which isnt loaded properly from my API, since the new post isnt showing.
I route back to the overview with
Location.replace('../nyheder');
How do i clear cache while routing to another page?
I rather think it is an issue with your HTTP -mainly response- headers. The headers will tell Chrome whether to fetch new data or use its cache.
You should use
If-none-match
and
ETag
Headers.
Related
I'm building a web app (well at least one page on it) that shows the results of pings to different IPs.
I have no probs on Go displaying them on an HTML page. The simple thing I can't do (and I read so many tuto/threads that I'm lost and don't know what to do....) is to create a button "Refresh" that could just call back the "pingip" function i created in Go file.
Anyone has a concrete/"easy" example on how I could do this?
Assuming you have a HTTP Handler for your Go program, which is what is serving the page - then you can have the button simply do a window.reload() through JavaScript, which will reload the page in the browser and re-invoke the Go script.
If you want this to happen without a reload, then you'd have to create a different HTTP Route and use AJAX (look up the fetch method in JavaScript), get the results over the network (maybe as JSON) and then update the data in the frontend.
In one of the online documents that talks about appcache for HTML5, it indicates that the cached files get updated once an offline user reconnects. I checked the original HTML5 appcache definition by W3, and I am not able to find anything that supports this statement.
Does anyone know if this is to be true?
Thanks in advance
MDN says the following, although if you scroll up on that page it says it's being deprecated.
If an application cache exists, the browser loads the document and its associated resources directly from the cache, without accessing the network. This speeds up the document load time.
The browser then checks to see if the cache manifest has been updated on the server.
If the cache manifest has been updated, the browser downloads a new version of the manifest and the resources listed in the manifest. This is done in the background and does not affect performance significantly.
And logic tells me that it would also depend on the app you're using, server you're trying to connect to and any special settings it might have, how long your browser keeps it's history, what it keeps, and if you saved the page to view offline - whether or not you have all the code/images saved in the right location(s).
Example:
Imagine you saved a page to view offline, and that page has a JS event handler that ran a while loop that did an ajax request every n seconds to do something, like make a number on a page change as long as you were online... As long as the loop is running, you suddenly connect to the internet, and it makes the request to the proper url with the right arguments, then it should go through, even though the url in your browser might say something like file:///C:/Users/you/Desktop/....
I've done this before, even though my url was like the one above. One time I was using braintree's drop-in javascript to a website, and using it's api on my backend. Trying to load the page when offline = Nothing. Online = Updated the spot on the page just fine when I had the required arguments, and it was pointing to the right url. If I got offline again, I could refresh the page, see the same images loaded in the <div>, but I couldn't send any data with it.
I'm trying to to guarantee that fresh JSON is sent to my page every time a user clicks refresh. Currently, if the JSON is updated the webpage will not reflect the change until Apache is restarted.
I have tried the following approaches -
Create a nocache function and call the decorator in the page function
I have tried putting headers in my HTML
Using Command + Shift + R in Chrome for MacOS for a "hard" refresh
No good... I'm beginning to think I'm misunderstanding something. Can someone point out the error of my ways? I copy and pasted the code presented in those links. The first link even speaks about JSON specifically. I can show my exact code being used if desired, but like I said; copy and paste.
Maybe its not even a caching issue, I'm not sure, but I'm open to any ideas!
EDIT:
I know now that my no-cache headers ARE being passed to the HTML. The issue lies somewhere in that the Flask isn't asking MySQL for updated data every time the page is loaded, only when Apache is restarted. So even if fresh data is in MySQL DB it will not be displayed for the user unless Apache gets restarted.
I finally found another post on Stack Overflow regarding my question.
Turns out I need to make my DB connection and form the JSON in the same function. Before I was calling the data from the DB in a separate function and then referencing it to create JSON and pass it to the HTML in a different one. Now everything is inline see HERE.
I know from the Postman docs that I can open saved requests in a new tab either by creating a new tab before clicking on the saved request or with a keyboard shortcut, but I'm hoping there's a way to default Postman to always open requests in new tabs - like the standard functionality of most IDEs.
I frequently find that I've sent a request, then a second, different one and wish I could check something in the response for the first request, but it's no longer there, because the second request opened over the first.
Obviously if I know that I'm going to want the first response, I can explicitly save it, but that's quite cumbersome, and it's usually only after I've sent the next request that I realise I want to refer back.
I suspect the answer is probably to build muscle memory to always hold Ctrl + Shift when clicking a saved request, but it would be nice if there was a setting.
Just realised that this is now possible (or perhaps always was and I just missed it) - in the 'General' tab of the Settings dialog, under the heading 'REQUEST' is a switch for 'Always open requests in new tab'.
There is a setting for this. This image will help:
I've recently added HTTP headers to my site to inform the browser to check with the server every time it comes across a given JS/CSS URL. I've tested it and it works perfectly; all browsers now make conditional GET requests.
Here's the problem though -- people still have the old headers cached; headers which more or less told the browser "cache this forever; don't bother asking for an update!". This can be busted with a hard refresh. I don't want to have to communicate to everyone to please hit F5 on any buggy pages after we push out code.
Are there any HTTP header(s)/HTML meta tag(s) I could put on the HTML document itself to say "Browser, ignore the headers you have on the JS/CSS files and download the latest version of all the included files on this page"?
Eventually this problem will work itself out as more and more people clear their cache or learn to refresh on their own. But, I'd rather fix it now. Then in a month or so, I'll remove the HTML-level headers to get caching where I want -- on a per resource basis.
EDIT: I do not want to rename the resources or add on query parameters. That's what we used to use (?v=18, ?v=19, etc.) and it was a chore to increment that number every time we updated resources. Even doing that programmatically isn't the ideal solution; especially now that our server is configured correctly. It makes more sense to do it on the HTTP level so it works regardless of how you're accessing it -- included on a page, directly from the address bar, or otherwise.
pass a parameter to on the script source which will force a reload of the script... in fact you could do it by version or similiar
<script src="/test/script/myawesomescript.js?ver=1.0&pwn=yes" ...>
that would work and be seemless to the other users... when you feel like it has been long enough go back to the old way. but this will work if you want to force a refresh from users.
This method is utilized to prevent caching of webpages by some frameworks. Let me know if you were successful
http://css-tricks.com/can-we-prevent-css-caching/ -- here is a link to the concept for css (should work in js too) -- the biggest difference is you dont want it to never cache, so dont use a time stamp, use my style like from above :) enjoy!
Basically the only way is to get the browser not to use the cached URL.
One method is to use a cache-busting dummy parameter on the end of the URL.
some-name.css?q=1
That will force the browser to reload that file (because that URL isn't in the cache), and the downloaded file won't be cached because of your new headers. However: you may need to use this new name indefinitely, because you can't guarantee that once you leave off the dummy parameter again the cached version may still be used.
The other method is to completely rename the file.
my-new-name.css