Related issues:
- https://github.com/uBlockOrigin/uBOL-issues/issues/5#issuecomment-1575425913
- https://github.com/w3c/webextensions/issues/403
Currently, there is no other way to inject CSS user styles than to
wake up the service worker, so that it can inject the CSS styles
itself using the `scripting.insertCSS()` method.
If ever the MV3 API supports injecting CSS user styles directly
from a content script, uBOL will be back to be fully declarative.
At this point the service worker is very lightweight since the
filtering is completely declarative, so this is not too much of
an issue performance-wise except for the fact that waking up the
service worker for the sole purpose of injecting CSS user styles
and nothing else introduces a pointless overhead.
Hopefully the MV3 API will mature to address such inefficiency.
Specifically, avoid long list of hostnames for the `matches`
property[1] when registering the content scripts, as this was causing
whole browser freeze for long seconds in Chromium-based browsers
(reason unknown).
The content scripts themselves will sort out which cosmetic filters to
apply on which websites.
This change makes it now possible to support annoyances-related lists,
and thus two lists have been added:
- EasyList -- Annoyances
- EasyList -- Cookies
Related issue:
- https://github.com/uBlockOrigin/uBOL-issues/issues/5
These annoyances-related lists contains many thousands of specific
cosmetic filters and as a result, before the above change this was
causing long seconds of whole browser freeze when simply modifying
the blocking mode of a specific site via the slider in the popup
panel.
It is now virtually instantaneous, at the cost of injecting larger
cosmetic filtering-related content scripts (which typically should
be garbage-collected within single-digit milliseconds).
Also, added support for entity-based cosmetic filters. (They were
previously discarded).
---
[1] https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/scripting/RegisteredContentScript
What does not work at the time of commit:
Cosmetic filtering does not work:
The content scripts responsible for cosmetic filtering fail when
trying to inject the stylesheets through document.adoptedStyleSheets,
with the following error message:
XrayWrapper denied access to property Symbol.iterator
(reason: object is not safely Xrayable).
See https://developer.mozilla.org/en-US/docs/Xray_vision for more
information. ... css-declarative.js:106:8
A possible solution is to inject those content scripts in the
MAIN world. However Firefox scripting API does not support MAIN
world injection at the moment.
Scriptlet-filtering does not work:
Because scriptlet code needs to be injected in the MAIN world,
and this is currently not supported by Firefox's scripting API,
see https://bugzilla.mozilla.org/show_bug.cgi?id=1736575
There is no count badge on the toolbar icon in Firefox, as it
currently does not support the `DNR.setExtensionActionOptions`
method.
Other than the above issues, it does appear uBO is blocking
properly with no error reported in the dev console.
The adoptedStyleSheets issue though is worrisome, as the
cosmetic filtering content scripts were designed with ISOLATED
world injection in mind. Being forced to inject in MAIN world
(when available) make things a bit more complicated as uBO
has to ensure it's global variables do not leak into the page.
