keyboardevent-key-standardiser-shim

KeyboardEvent key standardiser shim

This project is in an alpha state, and needs testing. Use in a production environment is not recommended.

Internet Explorer, Edge, and Firefox 36 and older (Firefox up to 48 in case of some media keys) suffer from non-standard event.key values. This shim fixes most (or at least the most common) of those. It doesn't polyfill event.key if it doesn't exist natively, but it plays well polyfills that do, such as https://github.com/cvan/keyboardevent-key-polyfill.

Usage

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

import 'keyboardevent-key-standardiser-shim';

The KEYMAP is exported in case you want to customise the shim. The main scenario for doing so would be to switch the numpad Decimal and Separator keys to use , and . instead of the other way around.

import { KEYMAP } from 'keyboardevent-key-standardiser-shim';

// Modern browsers return either ',' or '.' for the numpad "Decimal", depending on region.
KEYMAP.Decimal = ',';
KEYMAP.Separator = '.';

Implementation details

It is not possible, or at least not straightforward, to directly detect whether KeyboardEvent.prototype.key follows the latest standard. This shim instead replaces the native getter and returns a standard-complient key. Furthermore, if it notices a verified good key, it unloads itself and reverts to fully native event.key handling.

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 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