firefox-extension | Firefox extension beginning with Firefox | Addon library

In reading about the File API and wanting to write data directly from an indexedDB database to the client disk instead of first building and holding a large blob in RAM to download to disk, there are a few basic items I'm not understanding.

In the MDN documents these two statements are found:

In Gecko, privileged code can create File objects representing any local file without user interaction.

If you want to use the DOM File API in chrome code, you can do so without restriction. In fact, you get one bonus feature: you can create File objects specifying the path of the file on the user's computer. This only works from privileged code, so web content can't do it.

1. Where exactly does one write chrome code and/or Gecko priveleged code? Is this beyond a web extension? I've read and experimented with extensions; so, I'm not asking specifically about how to access them.

I'm not concerned about a 'normal' web page and server accessing the client disk. I know that it's not permitted inorder to protect the individual.

I'm interested in what can be done offline through the browser--with the aid of web extensions and/or a separate profile granting special permissions but without node.js, electron, etc.-- by an individual who knowingly wants to use the browser to do maybe what they should have built in the OS rather than the browser.

1. Put another way, if I want to use the browser just to run my javascript code to perform tasks all offline on my own machine, where is the privileged code written that gives access to these types of APIs that aren't subject to the security issues of a normal web page?

2. Is it still javascript or C++ in these areas?

Thank you.

This old question provides a link to their extension which includes the File API that writes to disk in a way that appears to provide a means to bypass the creation of a large blob of data. It's six years old but appears to contain what is needed, at least to get started.

I'm not referring to their trying to get around using indexedDB, but just that using this type of extension could allow for writing each object from the database directly to the client disk without first having to generate a large blob to download.

Attempt at employing Andrew Swan's suggestion

I'm trying to put the pieces together but have reached a point where am not sure how to continue. I wrote the code below in the background script of an extension. In attempting to employ Andrew Swan's suggestion, the plan is to intitiate a GET request for a text/csv file, which is intercepted and replaced by data extracted from database and written to the GET request by the stream filter.

First, make a GET request to a bogus url and listen for response, as follows:

I would like to create a WebExtension that provides toggle buttons for some of the settings in about:config (e.g. permissions.default.image).

• Is it possible to do this in WebExtensions?
• If so, what is the API?

I belive that this question predates WebExtensions: A Firefox extension that changes a value in the about:config

This question is actually about print dialogs: Is it possible to set config settings on Firefox from a Addon

I'm actually adding a button on a website to install a web extension and I would like to have a callback telling me if it was successfull or not.

I came accross documentation showing this code to do so :