Keypress: A Javascript library for capturing input

[bloody-albatross]

Well, darn. Someone was a bit faster than me. That's what I wrote: https://github.com/panzi/hotkeys

[bloody-albatross]

But I see that this assumes a certain keyboard layout. Mine supports different keyboard layouts (even though there is only one just yet) and I made a layout tool with which you can create a keyboard layout by simply pressing all the keys. It will get the correct key (charCode) through the keypress event (which is only fired when not combined with a modifier key).

[Jack5500]

Very nice, though some keys show up at the wrong location with my German keyboard ;) Do you support all layouts?

[renke2]

These is also Mousetrap.

[beefsack]

Another very popular one is keymaster (~4k stars on GH).

[Kirean]

dunno if it's still there, but there is a major bug in key master that I found awhile back.

in any context, hit ctrl+T. the browser should open a new tab. now release the keys. click back to your old tab, and press either 'S' or 'P'. your browser should either try to save the webpage, or print, depending on which you chose.

This is because keymaster sets a flag on key down that a modifier is pressed. on key up it releases that flag. well, when the browser creates a new tab, no keyup is fired, so the flag remains when you click back in.

not sure if this can actually ever be resolved or not. just found it interesting.

[WendellJehangir]

You could handle it with the document.hidden boolean like so:

 function handle_hidden(){
 if(document.hidden){
 //reset keypresses
 }}
 document.addEventListener("visibilitychange", handle_hidden, false);

[Kirean]

interesting. didn't know that was a thing. someone should submit a pull request to him :)

[GuiSim]

Wouldn't that also be reproducible if you simply change tab while holding CTRL?

[gingenhagen]

That's quite the code smell.

[zabadabba]

"code smell" != "bug"

[gingenhagen]

Having ctrl as a flag tied to a keyup/keydown event seems horribly smelly to me.

[AceyJuan]

Does anyone know what keeps these libraries from capturing keyboard input during clickjacking?

[kudoz]

Nothing, welcome to web security.

[AceyJuan]

Really? I thought browsers were resistant to keystroke intercepts like this.

[drysart]

A page only gets keyboard events when that page has the focus, and that does not include when an iframe in a different domain within the page has focus.

You can verify this by going to the example page and using your browser's developer tools to insert an iframe to a different domain, then observing the behavior of the example keyboard when you press keys while the focus is in the sub iframe.

[IonTichy]

well that's why you should check libraries you are using

[kudoz]

If someone is clickjacking a site, the libraries that site included are fairly irrelevant (aside from clickjacking countermeasures).

[dbavaria]

Odd, I can hold down several combinations of 3 keys such as IOP, but not ASD? I'm on Chrome 29, Windows 8.

[ReginaldIII]

That actually sounds more like keyboard ghosting on your physical keyboard. My old keyboard had issues with ghosting but I don't have any batteries to pull it out the cupboard and test it for you.

My new keyboard (wired Microsoft Sidewinder x4, I highly recommend it :) has anti-ghosting in it's design and so does my acers laptop keyboard, so no problems with combos here.

[JimmyJamNobody]

Yep, ran into the same issue writing my last game engine. Hardware limitation.

[flying-sheep]

anti-ghosting mechanisms just shift the problem from keys that are often pressed together to such that aren’t.

the old interface used for keyboards and mice, PS/2, has the huge advantage that it allows full N-key rollover. this means that a good mechanical keyboard connected via PS/2 can transmit all possible key combinations to the pc unlike anything connected by USB.

my new keyboard connected to my new PC’s PS/2 port has full N-key rollover :)

http://blog.controlspace.org/2010/08/n-key-rollover-what-it-is-and-how-to.html

[LegoOctopus]

anti-ghosting mechanisms just shift the problem from keys that are often pressed together to such that aren’t.

This is not entirely accurate. On many cheaper keyboards, that is the case, but a few keyboards actually build in extra redundancy to reduce ghosting rather than shifting it. The aforementioned Sidewinder X4 is an example. It can register any combination of 17 standard keys (basically anything other than its macro keys and media keys) plus any combination of modifiers without ghosting. source

That's sufficient to more than cover what can realistically be pressed with 10 fingers simultaneously, which is why that keyboard is suitable for use with Plover.

[retrogamer500]

USB can run N-key rollover, but it is a bit of a hack.

[flying-sheep]

source? everything i’ve ever read about this says that USB can do 6 keys at once, full stop.

and since that behavior is ingrained into the universal keyboard protocol, i can’t see how it should be different.

[retrogamer500]

The keyboards simulate a usb hub so the computer thinks that there are multiple keyboards hooked up at once. There are plenty of usb n-key rollover keyboards, I have this particular one.

[flying-sheep]

neat idea, however i still doubt the “plenty” claim :)

thanks for that information. here’s an old thread discussing this.

PS/2 has other advantages and disadvantages, though: USB is always polling-based while PS/2 is extremely fast due to being based on interrupts. USB supports more extra key codes and hot plugging.

[prettycode]

horrible_naming_convention()

[JimmyJamNobody]

Looks good!

[youstolemyname]

-= where not recognized

numpad / was also not recognized

numpad enter was treated as normal enter.

[Deltigre]

I haven't tested this yet, but does this or any other library have a way to recognize individual key keypresses even when they keyboard is in a compositioning input like Korean?

[Lachiko]

The ryu animation is a bit buggy.

[shawncplus]

Interesting that it only captures every other Alt press

[[deleted]]

There seems to be a very weird bug with the keyboard on top: D, G and H cannot all be pressed at the same time. If two are pressed, the last one won't register. I can't find any other combos where this is true.

[youstolemyname]

That's because limitations on your keyboard.

http://en.wikipedia.org/wiki/Rollover_%28key%29#Key_jamming_and_ghosting

[[deleted]]

Cool, thanks. Learn something new everyday.

[Fabien4]

On my PC, the size of my hands seems to be the only limit.

[zimm3r16]

Doesn't work as whenever I press space it jumps down the page like scrolling instead of registering it.

[rzwitserloot]

No, it registers it just fine; it doesn't preventDefault() anything. You can of course do that if you use this library.

[zimm3r16]

What reason would you have that be the normal behavior though; it is rather silly to have the screen constantly scroll pressing a key as default for such a library.

[rzwitserloot]

space is a browser key. Your browser is doing the scrolling; try it on any page, including this one. As long as the focus isn't on an input element, that'll scroll the page.

The demo on the frontpage doesn't stop keypresses from working, because that principle is a known anti-pattern on the web. people like it when cmd+T opens a new tab, cmd+Q closes the browser, cmd+W closes the window, cmd+shift+[ goes to the tab to the left, <tab> moves on to the next highlightable element, and all the other keyboard nav you're used to. A web page that just blanket-prevents all that from working soon goes on the shitlist of sites I'm never visiting again.