Prerequirement: node.js and firefox.
Install dependency after cloning the repository to your local working copy.
% git clone https://github.com/cat-in-136/firefox-prefjs-surveyer.git
% cd firefox-prefjs-surveyer
% npm i
Execute fetcher.js to obtain all default prefs.
% node fetcher.js /path/to/firefox > prefall.json
Do same procedure with another version of Firefox.
And then, we assume that we have two json file: prefall-old.json and prefall-new.json.
Run surveyer.js to obtain the diff table.
% node surveyer.js prefall-old.json prefall-new.json > diff.html