Caching specific Javascript and CSS files

Question

How can I cache a few specific JavaScript & CSS files. I found advice from this site to put this in my .htaccess file

AddOutputFilter DEFLATE css js
ExpiresActive On
ExpiresByType application/x-javascript A2592000

But it is incomplete. What is .htaccess and how do I create it, where to store it, in my web root folder?

What is the meaning of the following statements:

AddOutputFilter DEFLATE css js
ExpiresActive On
ExpiresByType application/x-javascript A2592000

I dont want to cache all my Javascript & CSS files rather just a few specific files which will never change.

How can I do this?

What web server are you using? .htaccess is a control file for the Apache web server. If you are using IIS it has no meaning. — Oded
– Oded, Commented Sep 24, 2011 at 18:29
i will use IIS...so please advise me what should i do. what i need to write in my asp.net file to cache few specific js & css file. plzz discuss in detail. thanks — Keith Costa
– Keith Costa, Commented Sep 24, 2011 at 18:31

Community · Accepted Answer · 2020-06-20 09:12:55Z

25

You can configure IIS to cache specific files by extension. For example:

Select the folder where your css/js files reside and then click on Output Caching. enter image description here

Then add the file extensions that you want to cache:

enter image description here

I don't think you can specify which ones to cache on a per file basis unless you write an http ~~handler~~ module to add the appropriate headers for each file independently, but from IIS this is how is done.

Then you can verify that you are getting 304 responses using firebug / fiddler or your tool of choice.

I hope this is helpful.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Sep 25, 2011 at 0:22

Icarus

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3 Comments

Keith Costa Over a year ago

can i cache js & css file by http handler....if so can point me any good article for this.

Icarus Over a year ago

@user750398 look at this article: blog.sb2.fr/post/2008/11/21/…

Tyler Forsythe Over a year ago

Output Caching is not the same as controlling browser cache. They are quite different. Output Caching allows IIS to internally cache dynamic page content so that it can serve it to the client faster. It has no effect on the client's browser cache.

cristobal · Accepted Answer · 2011-09-28 16:34:16Z

1

That's cool i would anyways add a file revisions and make IIS cache css + js files. As Icarus specified.

Then if you update the files on the server just add a new revision number this could also be a timestamp.

answered Sep 28, 2011 at 16:34

cristobal

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cristobal · Accepted Answer · 2011-09-24 23:53:56Z

AddOutputFilter DEFLATE: output is compressed(usually gzip) before sent to server in this case css & js your css and js.
ExpiresActive On: Sets Expires and cache control headers to On
ExpiresByType: Set the expire rule for the content type in this case application/x-javascript to a month A2592000 => 24 * 3600 * 30 its in ms.

I would recommend to instead of handling specific js via .htaccess you should add a revisions number to your js files, ala:

<script src="link/to/file.js?rev=xxx"></script>

Then when you update your files just update the rev number. And your clients will automatically be served the new files.

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