Can javascript read/write local files

Hello peeps

there’s a reason I didn’t put this in client-side nor server-side. Let me state my question here more clearly.

Can javascript read/write local files via some user initiated .exe/activex control ? Or to put it more simply, can I use a browser to edit files via something less complex than launching a full apache war machine (the server software - not the indian)?

I need to have a quick way to edit data on my computer, and coding html/javascript is simple and what I need, but how can I possibly allow javascript write permissions ?