Copied from w3c/uievents#66 (comment) as it's more InputEvent related.

Proposal
We should fire 'beforeinput' after 'compositionupdate', e.g.

*'compositionupdate'
*'beforeinput'`
-update DOM now-
'input'`

Reasoning

1. Previously we want to fire 'beforeinput' before 'compositionupdate' because IE/Edge has a different behavior, but IIRC @gked mentioned that it was a bug and will be fixed. (@gked can you help confirm?)
2. If IE/Edge could update the behavior then it makes more sense to fire 'beforeinput' immediately before DOM update as required by spec:

   A user agent MUST dispatch this event when the DOM is about to be updated.

@whsieh Safari Technology Preview is firing 'beforeinput' after 'compositionupdate', just want to confirm: Is Safari going to ship with this order?