Displays and filters bookmarks on search string, show parent folders. This is a Mozilla Firefox Web Extension add-on version of the old "Bookmark search plus" XUL extension published by Alice0775 in its time, not working anymore in latest Firefox, and which was very useful.
It can be found on https://addons.mozilla.org/firefox/addon/bookmark-search-plus-2/
I regularly upload the source code here, at each release, labelling it with its version, so it should always be the latest. In case of doubt, the latest code is always in the .xpi itself (javascript is an interpreted language,), which is nothing else than a zip file => rename .xpi to .zip if you are on Windows, and open it with your favorite unzip tool. The source code is fully documented.