Is the 'input' event always queued before knowing whether its handler will actually be called?

Question

I have some code to be run:

• immediately after the input event handler if it's called
• when this handler would usually be called if it's not.

I noticed that queuing a message with setTimeout in the keydown handler works well.

In this demo, the logged sequence is the one we expect:

• With a regular input : keydown | input | end
• When an input is prevented in the keydown handler (try entering the letter 'b') : keydown | end
• When hitting a key that doesn't trigger an input ('Escape') : keydown | end

So it seems to me that the input event is queued before the keydown event is processed, when we don't really know yet whether there will actually be an input. It's just what I need, but how can I be sure things are actually supposed to be implemented this way?