Getting Resource interpreted as Script but transferred with MIME type text/html when I'm offline and requesting css and js files from AppCache

Question

I am developing a web app in which I am trying to use the HTML5 application cache.

I can successfully cache the files and load the files from AppCache while online. But when I go offline, all the css and js files are transferred with MIME type text/html instead of application/x-javascript or text/css, so it is not properly working on offline.

This is what I get when I request a page while offline.

Application Cache Error event: Manifest fetch failed (-1) https://example.com/manifest
Resource interpreted as Stylesheet but transferred with MIME type text/html: "https://example.com/offline_assets/stylesheets/cache/offline_all.css".
Resource interpreted as Script but transferred with MIME type text/html: "https://example.com/javascripts/offline/respond.min.js".
Resource interpreted as Script but transferred with MIME type text/html: "https://example.com/javascripts/yui3/3.1.1/build/yui/yui-min.js".
Resource interpreted as Script but transferred with MIME type text/html: "https://example.com/offline_assets/sprockets.js".

Therefore, the page is not styled and getting whole kind of JS errors.

How can I properly set such that css and js files are transferred with a proper MIME type from appcache while offline? thank you for your suggestions

Updated: this is how I serve the manifest file on the server

class ManifestController < ApplicationController

  def show
    headers['Content-Type'] = 'text/cache-manifest'
    render :text => File.open("#{RAILS_ROOT}/public/manifest.appcache").read, :layout => false
  end
end

and I have passed this validation test: http://manifest-validator.com/

Here is my Manifest file:

CACHE MANIFEST
#<
/offline_assets/stylesheets/cache/offline_all.css
/offline_assets/fonts/websymbols-regular-webfont.woff
/offline_assets/javascripts/yui3/3.1.1/build/yui/yui-min.js
/offline_assets/sprockets.js
/offline_assets/javascripts/offline/respond.min.js
/offline_assets/images/logoClio.png
/offline_assets/images/search/icoSearch.png
/offline_assets/images/icoArrow-down.png
/offline_assets/images/gold/submenu_current.png
/offline_assets/images/calendar/left_arrow.gif
/offline_assets/images/calendar/right_arrow.gif
/offline_assets/images/calendar/left_arrow_on.gif
/offline_assets/images/calendar/right_arrow_on.gif
/offline_assets/images/calendar-lg.gif
/offline_assets/images/logo-tagline.gif
/offline_assets/images/icoRecent-matter.png
/offline_assets/images/icoRecent-contact.png
/offline_assets/stylesheets/yui/dt-arrow-dn.png
/offline_assets/stylesheets/cache/sprite.png
/offline_assets/images/timer_stop.png
/offline_assets/images/add3.png
/offline_assets/images/arrow_down.gif
/offline_assets/images/spinner.gif
/offline_assets/images/timer_start.png
/offline_assets/images/delete.png
/offline_assets/images/offline/logoClio.png
/offline_assets/images/offline/bgSteps-1.png
/offline_assets/images/offline/bgSteps-2.png
/offline_assets/images/offline/bgSteps-3.png
/offline_assets/images/offline/icoReload.png
/offline_assets/images/offline/dt-arrow-dn.png
/offline_assets/images/offline/sprite.png
#>

# offline.html will be displayed if the user is offline and attempt to get uncached pages
FALLBACK:
/ /offline.html

# All other resources (e.g. sites) require the user to be online. 
NETWORK:
*

And this is one of the cached file that shows MIME type and other details on chrome://appcache-internals/

https://staging.goclio.com/offline_assets/sprockets.js?cec750eb3581f3d9f78c97d0ad8331df
HTTP/1.1 200 OK
Server: nginx/0.8.55
Date: Fri, 09 Mar 2012 19:56:17 GMT
Content-Type: application/x-javascript
Last-Modified: Fri, 09 Mar 2012 19:51:10 GMT
Expires: Thu, 31 Dec 2037 23:55:55 GMT
Cache-Control: max-age=315360000
X-Backend-Server: 333963-web02.rs.goclio.com:81
Accept-Ranges: bytes
Vary: Accept-Encoding, User-Agent
Content-Encoding: gzip

Another update: this works fine on firefox without getting any MIME type error. Naoya

Answer 1

It was actually not an issue of MIME type. It was giving me the text/html content-type error as it was returning offline.html which is returned when I request a non-cached file. The issue was that I added MD5 hash as a parameter for each file. so the manifest looked like this.

CACHE MANIFEST
/offline_assets/stylesheets/cache/offline_all.css?someMD5hash
/offline_assets/javascripts/yui3/3.1.1/build/yui/yui-min.jsf?anotherMD5hash
#and may more files with MD5 hash

FALLBACK:
/ /offline.html

NETWORK:
*

when it requested the content while offline, it was not able to find an appropriate file as the cached file name contained the MD5 hash as a parameter. So I resolved it by including the MD5 hash as the comment.