Need algorithm for how events are fired for key presses

[garykac]

Since it's more complicated than simply:

• keydown
• beforeinput
• keypress (deprecated)
• input
• keyup

For example, see whatwg/html#2605 which talks about inconsistencies in how UAs treat key presses in controllers.

Also cover how key events are handled during composition.

Starting proposal (needs to be verified):

global_state: inComposition = False

• if target is a controller, then
  • return
• send keydown event
• if keydown is not cancelled, then
  • if key triggers composition, then
    • set inComposition = True
    • send compositionstart event
    • if compositionstart event is cancelled, then
      • ...
    • send compositionupdate event
  • else if inComposition and key triggers exiting composition, then
    • send compositionend event
    • set inComposition = False
  • else
    • send beforeinput
    • if beforeinput event is not cancelled, then:
      • if inComposition, then
        • send compositionupdate event
      • Update the DOM
      • send input event
• send keyup

[domenic]

It seems like we'd need some kind of loop in there to handle the case where I hold down a key and don't let it go until several characters have been entered. That should trigger at least a few input events, I'd think?

[domenic]

Regarding integration with the input/composition events, my instinct would be to start with one big all-together algorithm then try to refactor if possible.

[garykac]

Draft proposal for an algorithm to specify how keyboard, input and composition events are fired:

https://docs.google.com/document/d/1LJQvjEmWZGzVgZnofpvdkxMj1hEnLniD72XD4DLJWx4/edit?usp=sharing