Hello,
Please see
https://jsblocker.toggleable.com
I find this extension very valuable and would like to see it have a future with Safari.
The web page above states:
Deprecated
JS Blocker downloaded from outside the Safari Extension Gallery will cease to function in Safari 12 and macOS Mojave (10.14). Developer-signed Safari extensions are not supported in Safari 12. Safari extensions distributed in the Safari Extension Gallery are deprecated, and Safari 12 is the last release to support them.
Safari App Extension
I have no experience creating native mac apps; it will therefore be impossible for me to re-create JSB as one.
Updates
Users who downloaded JS Blocker from the Safari Extension Gallery will probably not be able to update beyond 5.2.2. Apple is not responding to my requests for updates despite them saying they will accept submissions until the end of 2018.
I'd greatly appreciate if Apple would work with this developer to allow people to continue to use his product.
Thanks
Joe