KeyboardEvent key standardiser shim

Current Internet Explorer and Microsoft Edge, as well as Firefox 36 and older (mainly), suffer from non-standard event.key values. This shim fixes most (or at least the most common) of those. It does not polyfill event.key unless it exist natively, but it plays well polyfills that do, such as https://github.com/cvan/keyboardevent-key-polyfill.

Installation

npm install --save keyboardevent-key-standardiser-shim

Usage

The shim self-executes. Simply import it or require it.

import 'keyboardevent-key-standardiser-shim';

Keymap

Input	Standard key	IE	Edge	Firefox
Up	ArrowUp	current	current	36
Down	ArrowDown	current	current	36
Left	ArrowLeft	current	current	36
Right	ArrowRight	current	current	36
Del	Delete	current	current	36
Crsel	CrSel	11?	?	36
Exsel	ExSel	11?	?	36
Esc	Escape	current	current	36
Apps	ContextMenu	current	current	36
OS	Meta	-	-	current
Win 1	Meta	current	current	-
Scroll	ScrollLock	current	current	-
Spacebar	' '	current	?	36
Nonconvert	Nonconvert	11?	?	36
Decimal 2	. or , (regional)	current	current	28
Separator 2	, or . (regional)	current	current	28
Multiply	*	current	current	28
Add	+	current	current	28
Divide	/	current	current	28
Subtract	-	current	current	28
MediaNextTrack	MediaTrackNext	current	current	36
MediaPreviousTrack	MediaTrackPrevious	current	current	36
MediaFastForward	FastFwd	?	?	36
Live	TV	?	?	36
Zoom	ZoomToggle	11?	?	36
SelectMedia	LaunchMediaPlayer	current	current	36
MediaSelect 3	LaunchMediaPlayer	-	-	37 - 48
VolumeUp 3	AudioVolumeUp	current	current	48
VolumeDown 3	AudioVolumeDown	current	current	48
VolumeMute 3	AudioVolumeMute	current	current	48

¹ Note that event.metaKey is normally set to false on windows, even when Meta (Win) is pressed.

² It should be possible to use event.locale to dynamically map Decimal and Separator to the regionally correct keys.

³ Firefox 37+ will be considered by the shim as standard complient, so if you need this key on FF 37-48, considering checking for it specifically.

If you have the possibility to test complience of keys marked with a question mark, or if you find other browsers returning non-standard keys, then please report your findings (e.g. by opening an issue).

So far the shim and standard compatibility has been tested on:

• IE 11 (current)
• Edge 14, 16 (current)
• Firefox 23, 29, 36, 37, 55, 59 (current)
• Chrome 65 (current)

Notes:

• Firefox 23 - 28 returns "mozPrintableKey" for any printable key.

Implementation details

It does not seem possible to directly determine whether KeyboardEvent.prototype.key follows the latest standard, without listening to physical keyboard events. This shim therefore replaces the native getter and returns a standard-complient key. Furthermore, if it notices a verified good key (keys that in practice only standard complient browsers return), it unloads itself and restores fully native event.key handling.

The shim exports the KEYMAP as well as the VERIFIED_KEYS, in case you need to configure either.

This does not fix all event.key issues and bugs with older browser. E.g. Internet Explorer reports "Unidentified" for multiple non-latin modifier keys. Also, some browsers may in rare cases return the wrong key value, such as Firefox returning "AltGraph" instead of "ModeChange".

Further reading:

• MDN list of key values and exceptions
• Edge bug report