Core: New JS Extension API

[tobyzerner]

As per https://gist.github.com/tobyzerner/7613421bf93a953a33958e323d7ab67e

This will include some other specific changes:

• Refactor entity controls:

  • flarum/controls/DiscussionControls
  • controls = new DiscussionControls(discussion)
  • controls.items() (don't bother with different “sections”? Need to review the way approval/flags/akismet adding post controls currently works)
  • Better yet: discussionControls(discussion)

• ItemList improvements

  • Add a toVnodes method, remove the listItems helper
  • Allow method chaining
  • Consider these methods:
  • items.after('delete').add('something', hello)
  • items.before('delete').add('something', hello)
  • items.after('delete', 10).add() // specify a fallback priority
  • items.after(['foo', 'bar'], 10).add() // specify multiple items to add after

[franzliedke]

When this is done, we might want to consider #246 as closed?

[luceos]

Related to ItemList could you possible move the login related entries of the LoginModal into a ItemList while you're at this? With your fluent setters this would be awesome.

See https://github.com/flarum/core/blob/master/js/forum/src/components/LogInModal.js

This would allow an extension to disable default authentication (relates to #641) but already gives us more flexibility.

[KyrneDev]

I would love if the edit user modal could also be an item list.

https://github.com/flarum/core/blob/master/js/src/forum/components/EditUserModal.js

[franzliedke]

Do we want to move this to beta-9 now that the ItemList stuff has ben merged?

I guess this one should still be kept open, because "only" basic infrastructure (Webpack, heh) was done so far. In contrast to #851, which I will close in favor of some smaller issues, one per missing extender type.