Browser Keymap

A small library for doing sane key binding in the browser. It defines two
things:

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browserkeymap keys are represented by strings like "Shift-Space",
"Ctrl-Alt-Delete", or "'x'". The rules are:

* keypress events are represented as the character that was typed
between single quotes. They do not support modifiers because
browsers do not attach modifier information to keypress events.

* keydown events are represented as zero or more modifiers
(Shift-, Cmd-, Alt-, Ctrl-) followed by a key name.

* A key name is a capital letter for a letter key, a digit for a
number key, F plus a number for a function key, the symbol typed
by the key when shift isn't held down (one of `[\]'*,-./;=`), or
one of the names Alt, Backspace, CapsLock, Ctrl, Delete,
Down, End, Enter, Esc, Home, Insert, Left, Mod,
PageDown, PageUp, Pause, PrintScrn, Right, Shift,
Space, Tab, or Up.

You can get a key name from an event by calling
Keymap.keyName(event).

You can normalize a key name string (fixing the order of the
modifiers, and replacing alternative modifier names with their
standard name) by calling Keymap.normalizeKeyName(string). This
function maps the modifier Mod- to Cmd- on Mac platforms and to
Ctrl- on non-Mac platforms. It also accepts a- for Alt-, c- or
Control- for Ctrl-, m- or Meta- for Cmd-, and s- for
Shift-.

You can use Keymap.isModifierKey(string) to find out whether the
given key name refers to a modifier key.

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The Keymap constructor itself, which is the thing the library
exports, can be used to build keymaps.

var myMap = new Keymap({
"Ctrl-Q": handleQuit,
"Shift-Space": autocomplete
})

A keymap associates keys with values. You can call its lookup method
to look up a key:

myMap.lookup("Ctrl-Q") // → handleQuit
myMap.lookup("Alt-F4") // → undefined

You can create a new map from an existing map with its update
method:

var newMap = myMap.update({
"Alt-F4": handleQuit,
"Ctrl-Q": null
})

That will create a new map, starting with the bindings in myMap,
adding a binding for Alt-F4, and removing the binding for Ctrl-Q.

Multi-stroke keys are supported by providing space-separated names to
a keymap. When a prefix of a multi-stroke key is looked up, the
lookup method will return Keymap.unfinished`. The handler should
then buffer the key name, and on the next key event (possibly with a
timeout to clear buffered keys), try again by prefixing the new key
event's name with the buffered key(s).

License

This module is released under an MIT license.