Author: Steven Neiland
Published:

Warning: This blog entry was written two or more years ago. Therefore, it may contain broken links, out-dated or misleading content, or information that is just plain wrong. Please read on with caution.

So this morning I had to change gears and do some javascript debugging. I test the existing code and see the error, make my changes save them...and still see the same error wtf? For about 15 minutes I was completely confused as I could see the code changes saved in the file but when I ran firebug the inspector showed the old code.

Of course finally I figured it out, firefox caching. Here is the kicker though, I had been clearing my browser cache with ctrl-f5 but firefox was not actually clearing the javascript cache.

I don't know if this is a new behavior as I don't normally do javascript development but it is really stupid in my opinion. If I tell my browser to clear the cache I expect that to include javascript.

Clear Cache with Shortcut

There are a couple of ways of truly clear firefox's cache. One way is to clear all cache elements by using the "ctrl-shift-del" keyboard shortcut. Now I personally don't use this method so I can't confirm how effective it is.

If you are interested here is Mozilla Firefox's keyboard shortcut list.

Add On's

A more convenient method is to use a firefox addon to clear the cache. You can either use the "Firefox Web Developer Addon" which has a clear cache command, or if you want a quick shortcut you can use the "Clear Cache Button".

Always Off

While the above method's work, personally I am lazy. I don't want to have remember to clear my cache everytime I change a javascript file I am developing. I just want caching turned off all the time.

To do this enter about:config into the firefox address bar. This will open up firefox's configuration options.

network.http.use-cache

This preference controls whether to cache files retrieved using http or https. Setting the value to false turns off caching of the javascript files (as well as other files). Now this does increase the number of resource requests, but on a developer machine I think its worth the tradeoff.

network.http.use-cache = false

More information about this option can be found at network.http.use-cache.

browser.cache.offline.enable

While not strictly related this caching option can also be handy. What it does is turn off the offline caching of data when not connected to the internet.

It is easy to confuse these two options so make sure you are setting the one you need.

browser.cache.offline.enable = false

More information about this option can be found at network.http.use-cache.

What Do You Think?

Reader Comments

alex's Gravatar
alex
Tuesday, October 1, 2013 at 1:15:11 PM EDT

Thank's for this article! great!

Julie's Gravatar
Julie
Thursday, December 12, 2013 at 5:14:24 PM EST

Thanks for this! It helped a lot!

Charlotte's Gravatar
Charlotte
Sunday, June 15, 2014 at 4:57:58 PM EDT

Thanks for the article :-)

What's the difference between network.http.use-cache
and browser.cache.offline.enable

What do each do on their own?

Steven Neiland's Gravatar
Steven Neiland
Monday, June 16, 2014 at 11:23:00 AM EDT

Charlotte,
The setting "browser.cache.offline.enable" determines if firefox downloads links resources for a page for use when the page is being displayed while offline.

The setting "network.http.use-cache" determines if a page itself will be cached.

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