my-hotkeys

Keyboard shorcuts.

Install

$ npm install my-hotkeys

Basic Usage

import {hotkeys} from 'my-hotkeys`;

const hk = hotkeys();

// bind one:
hk.bind('a', doSomething);

// or multiple:
hk.bind({
    'a': doSomething,
    'ctrl-a': doSomethingElse,
    'ctrl-alt-3': doAnotherThing,
});

hk.unbind('a'); // removes a hotkey

hk.unmount(); // removes the instance's event listener
hk.mount(); // adds the instance's event listener

hk.destruct(); // removes all hotkeys and the event listener

Index

• Creating an instance
• Binding / Unbinding Keys
• Mount/Unmount the event listener
• Hotkeys Strings
• Destruction

Creating an instance

There are two ways to get a Hotkeys instance:

1. By calling hotkeys creator function (lowercased "h")
2. By the Hotkeys constructor (uppercased "H")

import {hotkeys} from 'my-hotkeys`;

const hk = hotkeys();

or:

import {Hotkeys} from 'my-hotkeys`;

const hk = new Hotkeys();

The difference between them is that hotkeys creator function also mounts the event listener on creation and doesn't have the ignore function argument (yet). When using the constructor you need to call .mount() manually (see .mount() below) and you can also set an ignore function.

Both accept an optional argument as the context element (HTMLElement | Document). This would be the element that listens to the keyboard events. Defaults to document.

const hk = hotkeys(elmOrDoc);
// => internally: elmOrDoc.addEventListener()...

⚠ Non-browser environments: You might need to pass in the runtime's document object as the constructor argument.

Ignore Function

By default, the Hotkeys instance ignores key presses if the event.target element is:

• <input>
• <select>
• <textarea>
• [contenteditable="true"]

You can pass the constructor your own ignore function as the second argument. This function gets called on every keydown event with the event object. Return a truthy value to ignore the key press or a falsy value for continue executing the hotkey.

const hk = new Hotkeys(document, (ev: KeyboardEvent) =>
    ev.target === mySpecialElement);

Binding / Unbinding Keys

.bind()

• .bind(hotkey, callback) - hotkey string, callback
• .bind({hotkey: callback}) - an object of {hotkey:callback}

Adds keyboard shortcuts. Does not add an event listener.

hk.bind('a', doSomething);
hk.bind('b', doSomethingElse);

// or:

hk.bind({
  'a': doSomething,
  'b': doSomethingElse,
});

Each hotkey can be bound once:

hk.bind('a', doSomething);
hk.bind('a', doSomethingElse); // -> throws Error

Callback functions are called with the keyboard event as their only argument:

function doSomething (ev: KeyboardEvent) {...}

.unbind()

• .unbind(hotkey) - hotkey string
• .unbind([hotkey...]) - an array of hotkey strings

Removes keyboard shortcuts. Does not remove the event listener.

hk.unbind('a');
hk.unbind('b');

// or:

hk.unbind(['a', 'b']);

.unbindAll()

Unbinds all hotkeys. Does not remove the event listener.

hk.bind('A', doSomething);

hk.unbindAll();

hk.bind('B', doSomethingElse);

Mount/Unmount the event listener

Each Hotkeys instance can only have one keydown keyboard event listener. The event listener is attached to the context element passed in construction. Defaults to document.

• .mount() - Attaches the event listener to the context element.
• .unmount() - Dettaches the event listener from the context element.

const hk = new Hotkeys(myMenu);

hk.bind('Q', doSomething);

// user presses "Q" but nothing happens

hk.mount(); // => internally: myMenu.addEventListener()...

// user presses "Q" and `doSomething` is called

hk.unmount();

// user presses "Q" but nothing happens

Using the creator function mounts the event listener for you:

const hk = hotkeys(); //  <---- also mounts

hk.bind('Q', doSomething);

// user presses "Q" and `doSomething` is called

hk.unmount();

// user presses "Q" but nothing happens

Hotkeys Strings

Currently, my-hotkeys supports the classic/standard/canonical way of binding keys: there are modifier keys (Control, Alt, Shift, Meta) and all the rest ("regular" keys).

A hotkey string can be a single regular key, with or without modifiers.

Modifier keys cannot be hotkeys without a regular key, i.e. .bind('ctrl-alt') will not work.

You can also bind by event.code or by symbols like ?.

Delimiter

The delimiter character is -, not configurable (yet?). If you want to bind - as a hotkey - use its alias: "Minus" (e.g. 'ctrl-minus').

Examples:

hk.bind({
    'a': doSomething,
    'ctrl-a': doSomething,
    'ctrl-alt-a': doSomething,
    '?': showHelp, // by symbol that may require shift
})

Hotkeys are case insensitive:

hk.bind('ctrl-a', doSomething)
// Same as:
hk.bind('Ctrl-A', doSomething)

But not when you bind by a key id (event.code):

// event.code is case sensitive
hk.bind('Numpad8', doSomething)

Aliases

Some keys have aliases for better readability or just for convenience.

Aliases are case insensitive.

Modifier Aliases:

Regular Key Aliases:

Destruction

Call .destruct() when its context element leaves the DOM. It will remove all of the instance's hotkeys and event listeners by calling .unmount() and .unbindAll().

const hk = new Hotkeys();

hk.bind('A', doSomething);
hk.mount();

// ...

hk.destruct();