Using keyup makes no sense and is inconsistent with user expectations. For triggering actions (which includes normal typing), you only ever use keydown. (Well, there’s one exception for reasons unclear to me: activating a button by pressing Space. That triggers on keyup like how clicks are on release, while Enter triggers on keydown.) Keyup is limited to things where you’re constantly reacting to the state of a key, as is common in games.
This affects the functionality, too. It is in fact introducing latency by using keyup instead of keydown. Feels bad.
That’s where the input event is really useful as it allows for more input options than just keyboard and then you don’t have to deal with figuring out if it’s down or up.
For triggering actions (which includes normal typing), you only ever use keydown.
I think you have this wrong, actions generally occur on button release, until that you can move the mouse cursor to a different target, tab to another control, use [ESC] to cancel, and so on. Typing, moving a slider with the cursor keys, and similar things that make use of key repetition while holding down the key are the exception to this.
Can you give some specific examples? In my experience (which I also verified to make sure), all of the things you mention act on keydown. The exceptions are on multi-key combinations, which follow a special key that is held down while modifiers are entered, where the action is completed by releasing this special key (ALT + TAB [...TAB | SHIFT]) being a common example.
TAB is otherwise immediate, as is ESC, and the examples of typing, as well. So I'm left wondering, how do they have it wrong?
Key down is used for events that can be duplicated by holding the key. Eg in a text editor, when you want multiples of the same letters, you’d press and hold the key.
Key up is used for when it’s important to only have one occurrence of that event.
Technically you could write code that made key down only react once. But the logical separation makes some sense.
As a user, I’ve not thought too much about this before now. I agree with you mostly, but the keyup on space behaviour actually feels so innate I’d hate any change to it. Keydown on space is “jump”; nothing else.
I’d just like to hear an explanation of why it is. Because if you handled “is key currently pressed” events with polling rather than events (which is how people almost always consume them logically), it would be the only thing in the entire world that I can think of that would/should use keyup.
Edit: I think people are misunderstanding me. I’m asking for an explanation of why, when you have a button focused, pressing Space activates on key up, rather than key down like literally everything else on the keyboard, including Enter on a focused button. (Mouse activates on release.)
Because in those contexts, the Space key is being used as a physical mirror of the on-screen button, and on-screen buttons are UX'd to perform action when released.
These two interactions should behave identically:
- Hover over a button, press mouse button 1, release button 1.
- Tab over to a button, press spacebar, release spacebar.
Why on-screen buttons are UX'd to behave this way is a logical follow-up question. I'd wager that it gives a means to bail out of the clicking (e.g. by moving the mouse out of the on-screen button before releasing mousebutton 1, or by pressing Esc while having spacebar still depressed).
Yes, the bailing-out explanation is right. With a mouse it's intentional that you should be able to push the pointer off the button with the mouse button still pressed to cancel.
(Esc while Space is held doesn’t cancel, but Tab does.)
You’re only answering half of the inconsistency: because Enter activates buttons like any other key, on keydown.
It just matches real life. What about lmb to shoot? You don't fire a gun on trigger release, you fire it on trigger down. Walking? Would be weird moving only on keyup.
This raises the question of why real life buttons and virtual buttons behave differently. My unsubstantiated guess is that clicks act on release to give the opportunity to slide off the button to abort, and/or because the button would disappear while pressing if it ex. submits a form.
Jump is keydown because many games let you adjust your jump height based on how long you hold down space after the jump starts.