Local filesystem access in browser extensions

I'm doin开发者_开发技巧g some investigation into options for an app I am building. Do browser extensions for all browser platforms have filesystem access like Firefox does?

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Chrome extensions do not allow arbitrary filesystem access. You could, however, write an NPAPI plugin, but this comes with some heavy caveats:

You can also use HTML5 filesystem APIs to access a sandboxed filesystem:

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Dolphin browser looks to have it. Look at their API (I didn't test it yet). Hopefully it will help you.