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?

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:

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