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Why are my javascript files being read from cache

Hello
I have a problem where my javascript and css files are being read from the cache instead of when I do refresh for new content so it never updates. I am using firefox and wamp server and in firefox disabled privacy.trackingprotection, have selected always look for new pages in web developer tools and put wamp in offline mode.

Is it apache that is caching these files? Here is the exact message in the net tab of firebug. How can I solve this so my content is always updated. Thanks

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Dave Baldwin

They are being read from the browser cache because the file names match the request and the browser sees no indication that there are new versions on the server. Refreshing a page or even Ctrl-F5 refresh only refreshes the main page. It does Not automatically refresh JS and CSS files if the name remains the same. This is normal operation in all browsers that I know of.

peter-cooper

ASKER

@Dave

It does Not automatically refresh JS and CSS files if the name remains the same

actually it does. I just cleared cache and it loaded new files even though it is still showing as 200 OK (BFCache). How can I prevent this action as I do not want to clear cache each time I make updates to css or js file. Thanks

Dave Baldwin

You just confused two different things. Clearing the cache forces everything to be refetched because that's where it is all stored. Doing a 'page' refresh does not. Methods to force JS and CSS files to be updated when they are changed requires adding a query string with the version number or timestamp so they won't match the old version in the browser cache.

This question gets asked frequently because it is irritating to have to force the updates when you are developing. The idea of the cache is to speed up page loads when the files don't change. Makes it better for the user but irritating for the developer.

peter-cooper

ASKER

@Dave thanks for clearing that up. Do you have example how to code version number to file. Thanks

Dave Baldwin

It would look like "somejavascript.js?version=9". The version number does not have to actually be used by the code. The link in the browser must use it when you change the code. Even then, it doesn't get picked up until the new version of the page is downloaded.

Here is a discussion about it from last week.

https://www.experts-exchange.com/questions/29023735/Global-version-website-variable-for-clearing-cache.html

peter-cooper

ASKER

@Dave Thanks for link. However, I have 2 questions arising from such.

1) Do I have to change the version # each timeI update the CSS or JS file?

2) If so, is there a script that is available in php or jquery that could could randomise the version # and and replace with that version in the file name?

Thanks

Dave Baldwin

#1. Yes. That is the point, to make the version and thus the file name different from the previous version in the cache every time you change it.

#2. You could write one in PHP. jQuery runs in the browser so that is too late to affect the file names that are fetched. But why would you want to randomize them? I can't think of any use for that.

peter-cooper

ASKER

@Dave perhaps I should have said timestamp rather than randomize

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Dave Baldwin

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peter-cooper

ASKER

Thanks very much Dave. Exactly what I need. Cheers

Dave Baldwin

You're welcome, glad to help.