@rwh/keystrokes

If you encounter a bug please report it.

Keystrokes as a quick and easy to use library for binding functions to keys and key combos. It can also be used to check if keys or key combos are pressed ad-hoc. It supports any TypeScript or JavaScript project, and can be used in non browser environments too.

import { bindKey, bindKeyCombo } from '@rwh/keystrokes'

bindKey('a', () =>
  console.log('You\'re pressing "a"'))

bindKeyCombo('ctrl > y, r', () =>
  console.log('You pressed "ctrl" then "y", released both, and are pressing "r"'))

Installation

Keystrokes is available on npm. This works great when using a build system like Parcel, Vite, Turbopack, or webpack.

npm install @rwh/keystrokes

import { bindKey } from '@rwh/keystrokes'
bindKey('a', () => console.log('you pressed a'))

If node modules aren't an option for you, you can use an npm CDN such as jsDelivr or UNPKG.

<!-- ESM -->
<script src="https://unpkg.com/browse/@rwh/keystrokes@latest/dist/keystrokes.js">
<!-- UMD -->
<script src="https://unpkg.com/browse/@rwh/keystrokes@latest/dist/keystrokes.umd.cjs">
<script>
keystrokes.bindKey('a', () => console.log('you pressed a'))
</script>

Available Key Names

Keystrokes is environment agnostic, but by default will use built-in browser bindings. These bindings use the standard values for the KeyboardEvent.key property.

To see what key names can be used in your bindings see MDN's table of key values.

It is also possible to use KeyboardEvent.code should you care more about the key's location on the keyboard than it's value. To use code instead of key, prepend the key name with @. For example @KeyW binds the physical key labeled W on a QWERTY keyboard, Z on a AZERTY keyboard, and < on a Dvorak keyboard - the same physical key by position on all of these keyboards.

To see what code names can be used in your bindings see MDN's table of code values. Don't forget to prepend code names with @ when using them in bindings.

Note that if you need to bind a combo containing a key name like + which is used as a combo operator, you will need to escape the character using backslash.

Available Combo Operators

When using bindKeyCombo you will need to provide a combo expression. Combo expressions are made of units, and sequences.

Here is a table of operators:

Operator	Description
+	Key name separator - separates keys in a unit
>	unit separator - separates units in a sequence
,	sequence separator - separates sequences in a combo
\	Escapes a key name that is the same as an operator

Combo Unit

A combo unit is a grouping of key names separated by the + operator. Keys in a unit can be pressed in any order. One or more units make up a sequence, and are separated by the > operator.

In order for a unit to be satisfied all keys in the unit must be pressed, along with keys from units from earlier in the sequence. Units must be satisfied in order. For example the combo a + b > c can only be satified if unit a + b is pressed, then unit c (without releasing a and b).

Combo Sequence

Sequences are made up of units and are separated by the , operator. They enable the creation of multi-step combos. For example a + b > c, x > y is a combo made up of two sequences - a + b > c and x > y. Each of these contain two units a + b and c for the first, and x and y for the second. In order to satify this combo, a and b must be pressed (in any order), then c, then all must be released, then x, then y.

Binding Keys and Key Combos

Keystrokes exports a bindKey and bindKeyCombo function. These function will bind a handler function, or handler object to a key or key combo.

To bind a key you simply need to pass a key name to bindKey along with a handler function or object. As mentioned previously, the key names available depend on the bindings you are using. By default browser bindings are used, and these recognize the standard values for the KeyboardEvent.key property.

To bind combos you can pass a combo expression to bindKeyCombo. bindKeyCombo, like bindKey, will work with key names recognized by the bindings assigned to Keystrokes, and as mentioned these are browser bindings by default.

import { bindKey, bindKeyCombo } from '@rwh/keystrokes'

bindKey('a', () =>
  console.log('You\'re pressing "a"'))

bindKeyCombo('ctrl > y, r', () =>
  console.log('You pressed "ctrl" then "y", released both, and are pressing "r"'))

bindKey('a', {
  onPressed: () => console.log('You pressed "a"'),
  onPressedWithRepeat: () => console.log('You\'re pressing "a"'),
  onReleased: () => console.log('You released "a"'),
})

bindKeyCombo('ctrl > y, r', {
  onPressed: () => console.log('You pressed "ctrl" then "y", released both, then pressed "r"'),
  onPressedWithRepeat: () => console.log('You pressed "ctrl" then "y", released both, and are pressing "r"'),
  onReleased: () => console.log('You released "r"'),
})

Note that when you pass a function handler instead of an object handler, it is short hand for passing an object handler with a onPressedWithRepeat method.

const handler = () => console.log('You pressed "ctrl" then "y", released both, and are pressing "r"')

bindKeyCombo('ctrl > y, r', handler)
// ...is shorthand for...
bindKeyCombo('ctrl > y, r', { onPressedWithRepeat: handler })

Unbinding Keys and Key Combos

In more complex applications it's likely you'll need to unbind handlers, such as when you change your view. In order to do so you just need to keep a reference to the handler so you can unbind it.

import { bindKeyCombo, unbindKeyCombo } from '@rwh/keystrokes'

const handler = () => ...

// bind the combo to the handler
bindKeyCombo('ctrl > y, r', handler)

// ...and some time later...

// unbind the handler
unbindKeyCombo('ctrl > y, r', handler)

You can also wipe out all bound handlers on a combo by excluding a handler reference.

// unbind all handlers for the combo 'ctrl > y, r'
unbindKeyCombo('ctrl > y, r')

Checking Keys and Key Combos

If you have a situation where you want to check if a key or key combo is pressed at anytime you can do so with checkKey and/or checkKeyCombo

import { checkKey, checkKeyCombo } from '@rwh/keystrokes'

// keyIsPressed will be true if a is pressed, and false otherwise
const keyIsPressed = checkKey('a')

// keyComboIsPressed will be true if ctrl then y was pressed and r is pressed.
// It will be false otherwise.
const keyComboIsPressed = checkKeyCombo('ctrl > y, r')

Using Keystrokes with React

Keystrokes has it's own react specific package with a few goodies.

npm install @rwh/keystrokes @rwh/react-keystrokes

You will find two hooks, useKey and useKeyCombo, as well as an optional context provider which allows using these hooks with custom keystrokes instances.

Using it to track key or key combo states is rather easy.

import { useEffect, useState } from 'react'
import { useKey, useKeyCombo } from '@rwh/react-keystrokes'

export const Component = () => {

  const isComboPressed = useKeyCombo('a + b')
  const isKeyPressed = useKeyCombo('c')

  /* ... */
}

By default the hooks will use the global instance of keystrokes.

To use a custom instance of keystrokes you can wrap components using useKey and/or useKeyCombo with <KeystrokesProvider>. This component allows you to pass a custom instance of keystrokes, and all hooks rendered under it will use the provided instance instead of the global one.

See Creating Instances for more information on creating custom keystrokes instances.

import { useEffect, useState } from 'react'
import { Keystrokes } from '@rwh/keystrokes'
import { Keystrokes, KeystrokesProvider, useKey, useKeyCombo } from '@rwh/react-keystrokes'

export const Component = () => {

  const isComboPressed = useKeyCombo('a + b')
  const isKeyPressed = useKeyCombo('c')

  /* ... */
}

export const App = () => {

  const keystrokes = new Keystrokes({ /* custom options */ })

  return (
    <KeystrokesProvider keystrokes={keystrokes}>
      <Component />
    </KeystrokesProvider>
  )
}

Using Keystrokes with Vue

Like the react package there is also one for vue which is pretty similar to the react package, but with vue appropriate details.

npm install @rwh/keystrokes @rwh/vue-keystrokes

You will find two composables, useKey and useKeyCombo, as well as an optional composable, useKeystrokes, which acts as a context provider allowing the use of these composables with a custom keystrokes instance.

Using it to track key or key combo states is rather easy.

<script setup>
import { useKey, useKeyCombo } from '@rwh/vue-keystrokes'

const isPressedCombo = useKeyCombo('a+b')
const isPressedkey = useKeyCombo('a')

...
</script>

By default the hooks will use the global instance of keystrokes.

To use a custom instance of keystrokes you can wrap components using useKey and/or useKeyCombo with a parent vue component which calls useKeystrokes. This composable accepts an instance of keystrokes as it's first argument. The passed instance of keystrokes will be used by all composables in decendant components.

See Creating Instances for more information on creating custom keystrokes instances.

<script setup>
  import { Keystrokes } from '@rwh/keystrokes'
  import { useKeystrokes } from '@rwh/vue-keystrokes'
  const keystrokes = new Keystrokes({ /* custom options */ })

  useKeystrokes(keystrokes)
  
  ...
</script>

Testing your Keystrokes bindings

Keystrokes also exports a function, createTestKeystrokes, which creates an instance of Keystrokes modified for test cases. It has four additional methods for controlling the internal state.

import assert from 'assert'
import { createTestKeystrokes } from '@rwh/keystrokes'

describe('MyApp', () => {
  it('correctly handles the key combo', () => {
    const keystrokes = createTestKeystrokes()

    const app = new MyApp({ keystrokes })

    keystrokes.press({ key: 'a' })
    keystrokes.press({ key: 'b' })

    await app.update()

    assert(app.didComboBoundThing)
  })
})

If your app uses the global instance of keystrokes then this can be used in conjunction with setGlobalKeystrokes.

import { describe, it, expect } from 'vitest'
import { createTestKeystrokes, setGlobalKeystrokes } from '@rwh/keystrokes'

describe('MyApp', () => {
  it('correctly handles the key combo', () => {
    const keystrokes = createTestKeystrokes()
    setGlobalKeystrokes(keystrokes)

    const app = new MyApp()

    keystrokes.press({ key: 'a' })
    keystrokes.press({ key: 'b' })

    await app.update()

    expect(app.didComboBoundThing).toBe(true)
  })
})

Creating Instances

If you'd rather create your own instances of Keystrokes, rather than using the global instance, you can do so by constructing the Keystrokes class. Keystrokes class instance has all of the functions we've looked at above as methods.

import { Keystrokes } from '@rwh/keystrokes'

const keystrokes = new Keystrokes()

// All of the functions we've reviewed above are methods on the instance
keystrokes.bindKey(...)
keystrokes.bindKeyCombo(...)
keystrokes.unbindKey(...)
keystrokes.unbindKeyCombo(...)
keystrokes.checkKey(...)
keystrokes.checkKeyCombo(...)

If you want to go this route you won't have to work about overhead from the global instance as it is only created if you use the exported functions associated with it.

Configuration Options

Keystrokes has a few configuration options that you can configure by passing them to the Keystrokes constructor, or by calling the setGlobalKeystrokesOptions before using any of the functions exported by the package associated with the global instance.

Available Options

selfReleasingKeys?: string[] keyRemap?: Record<string, string>

Option	Description
selfReleasingKeys	Key names added to selfReleasingKeys will be marked as released after any other key is released. Provided to deal with buggy platforms.
keyRemap	An object of key value pairs with the key being the key to rename, and the value being the new name.
onActive	A binder to track viewport focus. See Non Browser Environments for details.
onInactive	A binder to track viewport blur. See Non Browser Environments for details.
onKeyPressed	A binder to track when keys are pressed. See Non Browser Environments for details.
onKeyReleased	A binder to track when keys are released. See Non Browser Environments for details.

Here is an example where we are configuring the global instance.

import { bindKey, setGlobalKeystrokesOptions } from '@rwh/keystrokes'

// Must be called before binding or checking keys or key combos
setGlobalKeystrokesOptions({
  keyRemap: { ' ': 'spacebar' }
})

bindKey(...)

And here is an example where we are passing the options to the Keystrokes constructor. These options will only effect the constructed instance.

import { Keystrokes } from '@rwh/keystrokes'

const keystrokes = new Keystrokes({
  keyRemap: { ' ': 'spacebar' }
})

keystrokes.bindKey(...)

Non Browser Environments

Should you wish to use Keystrokes in a non browser environment, you can do so with the use of the onActive, onInactive, onKeyPressed, and onKeyReleased binder options. Binders are functions that are called by keystrokes when constructed. The binder is passed a handler function. Your binder is expected to call this handler whenever the event associated with the binder occurs. Binders may also return a function which will be called when the library is unbound from the environment.

By default Keystrokes will internally setup binders that work with browser environments if you do not provide your own. This results in the same behavior as the following code.

import { Keystrokes } from '@rwh/keystrokes'

const keystrokes = new Keystrokes({
  onActive: handler => {
    const listener = () => handler()
    window.addEventListener('focus', listener)
    return () => {
      window.removeEventListener('focus', listener)
    }
  },
  onInactive: handler => {
    const listener = () => handler()
    window.addEventListener('blur', listener)
    return () => {
      window.removeEventListener('blur', listener)
    }
  },
  onKeyPressed: handler => {
    const listener = event => handler({ key: event.key, originalEvent: event })
    window.addEventListener('keydown', listener)
    return () => {
      window.removeEventListener('keydown', listener)
    }
  },
  onKeyReleased: handler => {
    const listener = event => handler({ key: event.key, originalEvent: event })
    window.addEventListener('keyup', listener)
    return () => {
      window.removeEventListener('keyup', listener)
    }
  }
})

keystrokes.bindKey(...)

Help Welcome

If you want to support this project by throwing be some coffee money It's greatly appreciated.

If your interested in providing feedback or would like to contribute please feel free to do so. I recommend first opening an issue expressing your feedback or intent to contribute a change, from there we can consider your feedback or guide your contribution efforts. Any and all help is greatly appreciated since this is an open source effort after all.

Thank you!