Do not fetch app.manifest each time

For creating an offline version of a bunch of link开发者_开发百科ed web pages I use an app.manifest-file that lists all the web pages for offline caching.

I would like it that the app.manifest file is not fetched every time when a user jumps from one web page to another. Most of the web pages will never be updated once the application is on the iPhone. Also the target audience is abroad so roaming costs could add up while users are using my "web app".

Searching the internet made me think in the direction of forcing an offline mode in Mobile Safari using Javascript but I don't know if this is the right way to go or if it is even possible.

Does anyone have any other and/or better ideas and suggestions on how to do this?

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I would try setting an expires header to the future for the manifest file. That should theoretically prevent the browser from making a request for it. Never tried it, though.