Declarative hotkey and focus area management for React

Related tags

react-hotkeys
Overview


React HotKeys

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A declarative library for handling hotkeys and focus areas in React applications.

Upgrading from 1.*.* ?

See the upgrade notes.

Looking for new maintainers

This package has been more or less unmaintained for over 6 months and is search of new maintainers to help address the many outstanding issues. If you are interested in helping out in any capacity, please get in touch.

Feature Overview

Basic Usage

Define a key map

import { HotKeys } from "react-hotkeys";
import MyNode from "./MyNode";
import React from 'react';

const keyMap = {
  SNAP_LEFT: "command+left",
  DELETE_NODE: ["del", "backspace"]
};

const App = () => {
  return (
    <HotKeys keyMap={keyMap}>
      <div>
        <MyNode />
        <MyNode />
      </div>
    </HotKeys>
  );
};

export default App;

Define handlers

import { HotKeys } from "react-hotkeys";
import React from 'react';

const MyNode = () => {
  const deleteNode = React.useCallback(() => {
    // logic here
  }, [])
  
  const handlers = {
    DELETE_NODE: deleteNode
  };

  return <HotKeys handlers={handlers}>Node contents</HotKeys>;
};

export default MyNode;

Contents

Licenses

react-hotkeys is released under the ISC License.

However, please note: the source code found in the lib/vendor directory is under the MIT License - please see the license file for each directory for more information.

Support

If you use React Hotkeys and it has saved you time or money, please consider contributing. You will be supporting react-hotkeys by supporting its maintainer.

Please see my Patreon Page for details of why your support is needed, and how it will be used.

For recurring and publicly acknowledged support:

Payment Option Link/Address
Patreon https://www.patreon.com/aleckgreenham

For one-off or irregular contributions:

Payment Option Link/Address
Paypal https://www.paypal.me/aleckgreenham
Bitcoin 1ETTdVEahUqBaGXRQaiEgMhVjYQU1jQKKT
Ethereum 0x6C9F9879f684e84314f5810f8F196bdB2c4e15c0
Stellar GBJ5T7V7YVRN4D2PBZTOCWREJXYWWGNDIQGRFDGQAZNTYYIW7BMWDRYA

Install

CommonJS & ES6 Modules

react-hotkeys is available as a CommonJS or a ES6 Modules through npm or yarn. It uses NODE_ENV to determine whether to export the development or production build in your library or application.

It is expected you will use a bundling tool like Webpack or Uglify to remove the version of the bundle you are not using with each version of your application's code, to keep the library size to a minimum.

The latest pre-release

npm
npm install [email protected] --save
yarn
yarn add [email protected]

Latest stable release

npm
npm install react-hotkeys --save
yarn
yarn add react-hotkeys

UMD

react-hotkeys as a UMD module is available on your CDN of choice.

Change 1.0.1 for the version that you would like to use.

Development build



Minified production build



Bower

Bower support was removed in v1.0.0, but those who already rely on earlier versions of react-hotkeys through Bower can continue to do so using the following command:

bower install [email protected]

The Bower version of the package will not be supported going forward (including fixing any outstanding issues).

Defining key maps

react-hotkeys uses key maps to decouple defining keyboard shortcuts from the functions they call. This allows hot keys and handler functions to be defined and maintained independent of one another.

When a user presses the corresponding combination or sequence of keys, it is said they match the hot keys, which causes an action to be triggered. react-hotkeys may then resolve an appropriate handler function to handle the action.

Key maps are Plain Old JavaScript Objects, where the keys are the action names and the values are usually a Mousetrap-supported or Browser Key Values sequence string (but can also be an array or an object) that must be matched in order to trigger the action.

const keyMap = {
  deleteNode: "del",
  moveUp: "up"
};

Key Combinations vs Sequences

Every hotkey or sequence string is parsed and treated as a sequence of key combinations. The simplest case is a sequence of 1 key combination, consisting of 1 key: e.g. 'a' or 'shift'.

// Key sequence with a combination of a single key
'4'

// Special single key sequence (ie. shift is handled automagically)
'?'

// Sequence of a single combination with multiple keys (keys must be pressed at the same time)
'command+shift+k'

// Sequence of multiple combinations (keys must be pressed and released one after another)
'up down left right'

Full Reference

Please refer to Mousetrap's documentation or Browser Key Values for an exhaustive list of supported shortcuts and sequences.

Alternative Hotkeys

You can specify multiple alternative key sequences (they will trigger the same action) using arrays:

const keyMap = {
  DELETE_NODE: ["del", "backspace"],
  MOVE_UP: ["up", "w"]
};

Specifying key events (keydown, keypress, keyup)

By default, react-hotkeys will match hotkey sequences on the keydown event (or, more precisely: on the keydown event of the last key to complete the last combination in a sequence).

If you want to trigger a single action on a different key event, you can use the object syntax and the action attribute to explicitly set which key event you wish to bind to:

const keyMap = {
  CONTRACT: "alt+down",
  COMMAND_DOWN: { sequence: "command", action: "keydown" }
};

If you want to change the default key event for all hotkeys, you can use the defaultKeyEvent option of the configuration API.

The full list of valid key events is: keypress, keydown, and keyup.

Specifying key map display data

You can specify data used to display the application's key maps using the object syntax and the name, description and group attributes (each are optional):

  {
    SHOW_DIALOG: { 
        name: 'Display keyboard shortcuts', 
        sequence: 'shift+?', 
        action: 'keyup' 
      }
  }

If you want to also provide alternative key sequences for the same action, use the sequences attribute:

  {
    SHOW_DIALOG: { 
        name: 'Display keyboard shortcuts', 
        sequences: ['shift+?', { sequence: '`', action: 'keyup' }], 
        action: 'keyup' 
      }
  }

Deciding which key map syntax to use

As a general rule, you should use the syntax that is the most brief, but still allows you to express the configuration you want.

Syntax Type Use when you ...
String Have a single key sequence and don't have any special requirements (Default case)
Array of strings Need alternative key maps that trigger the same action, and are happy with them triggering on the default key event
Array of objects Need alternative key maps that trigger the same action, and want to them to trigger on a different key event
Object Have a single key sequence and want to specify a different key event or display data
Object (sequences attribute) Have multiple key sequences that trigger the same action, and want to specify a different key event or display data

Defining custom key codes

When you are working in a WebOS environment, or a similar, you may have need to define custom key codes. You can do so using the customKeyCodes Configuration option:

import {configure} from 'react-hotkeys';

configure({
  customKeyCodes: {
    10009: 'BackTV'    
  }
})

Once defined, you are then able to use the key names in you action sequences:

const keyMap = {
  MY_ACTION: 'BackTV',
};

Setting dynamic hotkeys at runtime

react-hotkeys has basic support for setting dynamic hotkeys - i.e. letting the user set their own keyboard shortcuts at runtime. Once you have set up the necessary UI for viewing the current keyboard shortcuts (and opting to change them), you can then use the recordKeyCombination function to capture the keys the user wishes to use.

recordKeyCombination accepts a callback function that will be called on the last keyup of the next key combination - immediately after the user has pressed the key combination they wish to assign. The callback then unbinds itself, so you do not have to worry about tidying up after it.

recordKeyCombination returns a function you can call at any time after binding the listener, to cancel listening without waiting for the key combination to complete.

The callback function receives a single argument with the following schema:

{
  /**
   * Combination ID that can be passed to the keyMap prop to (re)define an
   * action's key sequence 
   */
  id: '',
  /**
   * Dictionary of keys involved in the combination
   */
  keys: { keyName: true }
}

// Example:

{
  id: 'a', 
  keys: { a: true }
}

If you are updating hotkeys without changing focus or remounting the component that defines them, you will need to make sure you use the allowChanges prop to ensure the new keymaps are honoured immediately.

An example, rendering two dialogs:

  • One for displaying the application's key maps using the getApplicationKeyMap function
  • Another for telling the user when to press the keys they want to bind to an action, meanwhile listening with recordKeyCombination()
import { recordKeyCombination } from 'react-hotkeys';
import React from 'react';

renderDialog(){
  if (this.state.showShortcutsDialog) {
    const keyMap = getApplicationKeyMap();

    return (
      <div style={styles.DIALOG}>
        <h2>
          Keyboard shortcuts
        </h2>

        <table>
          <tbody>
          { 
            Object.keys(keyMap).reduce((memo, actionName) => {
              const { sequences, name } = keyMap[actionName];
              
              memo.push(
                <tr key={name || actionName}>
                  <td style={styles.KEYMAP_TABLE_CELL}>
                    { name }
                  </td>
                  <td style={styles.KEYMAP_TABLE_CELL}>
                    { sequences.map(({sequence}) => <span key={sequence}>{sequence}</span>) }
                  </td>
                  <td style={styles.KEYMAP_TABLE_CELL}>
                    <button onClick={ () => this.showChangeShortcutDialog(actionName) }>
                      Change
                    </button>
                  </td>
                </tr>
              );
              
              return memo;
            })
          }
          </tbody>
        </table>
      </div>
    );
  } else if (this.state.changingActionShortcut) {
    const { cancel } = this.state.changingActionShortcut;
    
    const keyMap = getApplicationKeyMap();
    const { name } = keyMap[this.state.changingActionShortcut];
    
    return (
      <div style={styles.DIALOG}>
        Press the keys you would like to bind to #{name}.
        
        <button onClick={cancel}>
          Cancel
        </button>
      </div>       
    );
  }
}

showChangeShortcutDialog(actionName) {
  const cancelListening = recordKeyCombination(({id}) => {
      this.setState({
        showShortcutsDialog: true,
        changingActionShortcut: null,
        keyMap: {
          ...this.state.keyMap,
          [actionName]: id      
        }
      }); 
  });
  
  this.setState({
    showShortcutsDialog: false,
    changingActionShortcut: {
      cancel: () => {
        cancelListening();
        
        this.setState({
          showShortcutsDialog: true,
          changingActionShortcut: null
        }); 
      }
    }
  });    
}

Defining Handlers

Key maps trigger actions when they match a key sequence. Handlers are the functions that react-hotkeys calls to handle those actions.

Handlers may be defined in the same component as the key map:

import { HotKeys } from "react-hotkeys";
import React from 'react';

const keyMap = {
  MOVE_UP: "up"
};

const handlers = {
  MOVE_UP: event => console.log("Move up hotkey called!")
};

<HotKeys keyMap={keyMap} handlers={handlers}>
  <input />
</HotKeys>;

Or they may be defined in any descendant of the component that defines the key map:

import { HotKeys } from "react-hotkeys";
import React from 'react';

const keyMap = {
  MOVE_UP: "up"
};

const handlers = {
  MOVE_UP: event => console.log("Move up hotkey called!")
};

<HotKeys keyMap={keyMap}>
  <div>
    <HotKeys handlers={handlers}>
      <input />
    </HotKeys>
  </div>

  <div>
    <input />
  </div>
</HotKeys>;

Interaction with React

Rather than re-invent the wheel, react-hotkeys piggy-backs of the React SyntheticEvent and event propagation, so all of the normal React behaviour that you expect still applies.

  • Key events propagate up from a source or target towards the root of the application.
  • If an event has stopPropagation() called on it, it will not be seen by components higher up in the render tree.

HotKeys components

components listen only to key events that happen when one of their DOM-mounted descendents are in focus (

, , , etc). This emulates (and re-uses) the behaviour of the browser and React's SyntheticEvent propagation.

This is the default type of component, and should normally be your first choice for efficiency and clarity (the user generally expects keyboard input to affect the focused element in the browser).

HotKeys component API

The HotKeys component provides a declarative and native JSX syntax that is best for succinctly declaring hotkeys in a way that best maintains separation and encapsulation with regards to the rest of your code base.

However, it does require that its children be wrapped in a DOM-mounted node, which can break styling and add extra levels to your render tree.

<HotKeys
  /**
   * An object that defines actions as keys and key sequences as values
   * (using either a string, array or object).
   *
   * Actions defined in one HotKeys component are available to be handled
   * in an descendent HotKeys component.
   *
   * Optional.
   */
  keyMap={ {} }

  /**
   * An object that defines handler functions as values, and the actions
   * that they handle as keys.
   *
   * Optional.
   */
  handlers={ {} }

  /**
   * The type of DOM-mountable component that should be used to wrap
   * the component's children.
   */
  component={ 'div' }

  /**
   * tabindex value to pass to DOM-mountable component wrapping children
   */
  tabIndex={-1}

  /**
   * Whether the keyMap or handlers are permitted to change after the
   * component mounts. If false, changes to the keyMap and handlers
   * props will be ignored
   *
   * Optional.
   */
  allowChanges={false}

  /**
   * A ref to add to the underlying DOM-mountable node. Pass a function
   * to get a reference to the node, so you can call .focus() on it
   */
  innerRef: {undefined}
  
  /**
   * Whether this is the root HotKeys node - this enables some special 
   * behaviour
   */
  root={false}
  >

  /**
   * Wraps all children in a DOM-mountable component
   */
   { children }

</HotKeys>

withHotKeys HoC API

The HotKeys component API is generally recommended, but if wrapping your component in a DOM-mountable node is not acceptable, or you need more control over how the react-hotkeys props are applied, then the withHotKeys() HoC is available.

Simple use-case

The simplest use-case of withHotKeys() is to simply pass it your component class as the first argument. What is returned is a new component that will accept all of the same props as a component, so you can specify key maps and handlers at render time, for example.

The component you wrap must take responsibility for passing the hotKeys props to a DOM-mountable element. If you fail to do this, key events will not be detected when a descendant of the component is in focus.

import { withHotKeys } from "react-hotkeys";

class MyComponent extends Component {
  render() {
    /**
     * Must unwrap hotKeys prop and pass its values to a DOM-mountable
     * element (like the div below).
     */
    const { hotKeys, ...remainingProps } = this.props;

    return (
      <div {...{ ...hotKeys, ...remainingProps }}>
        <span>My HotKeys are effective here</span>

        {this.props.children}
      </div>
    );
  }
}

const MyHotKeysComponent = withHotKeys(MyComponent);

const keyMap = {
  TEST: "t"
};

const handlers = {
  TEST: () => console.log("Test")
};

<MyHotKeysComponent keyMap={keyMap} handlers={handlers}>
  <div>You can press 't' to log to the console.</div>
</MyHotKeysComponent>;

Pre-defining default prop values

You can use the second argument of withHotKeys to specify default values for any props you would normally pass to . This means you do not have to specify them at render-time.

If you do provide prop values when you render the component, these will be merged with (and override) those defined in the second argument of withHotKeys.

import { withHotKeys } from "react-hotkeys";
import React from 'react';

class MyComponent extends Component {
  render() {
    /**
     * Must unwrap hotKeys prop and pass its values to a DOM-mountable
     * element (like the div below).
     */
    const { hotKeys, ...remainingProps } = this.props;

    return (
      <div {...{ ...hotKeys, ...remainingProps }}>
        <span>My HotKeys are effective here</span>

        {this.props.children}
      </div>
    );
  }
}

const keyMap = {
  TEST: "t"
};

const handlers = {
  TEST: () => console.log("Test")
};

const MyHotKeysComponent = withHotKeys(MyComponent, { keyMap, handlers });

/**
 * Render without having to specify prop values
 */
<MyHotKeysComponent>
  <div>You can press 't' to log to the console.</div>
</MyHotKeysComponent>;

GlobalHotKeys component

components match key events that occur anywhere in the document (even when no part of your React application is in focus).

const keyMap = { SHOW_ALL_HOTKEYS: "shift+?" };
const handlers = { SHOW_ALL_HOTKEYS: this.showHotKeysDialog };

<GlobalHotKeys keyMap={keyMap} handlers={handlers} />;

generally have no need for children, so should use a self-closing tag (as shown above). The only exception is when you are nesting other components somewhere in the descendents (these are mounted before their parents, and so are generally matched first).

GlobalHotKeys component API

The GlobalHotKeys component provides a declarative and native JSX syntax for defining hotkeys that are applicable beyond you React application.

<GlobalHotKeys
  /**
   * An object that defines actions as keys and key sequences as values
   * (using either a string, array or object).
   *
   * Actions defined in one HotKeys component are available to be handled
   * in an descendent HotKeys component.
   *
   * Optional.
   */
  keyMap={{}}
  /**
   * An object that defines handler functions as values, and the actions
   * that they handle as keys.
   *
   * Optional.
   */
  handlers={{}}
  /**
   * Whether the keyMap or handlers are permitted to change after the
   * component mounts. If false, changes to the keyMap and handlers
   * props will be ignored
   *
   * Optional.
   */
  allowChanges={false}
>
  /** * Wraps all children in a DOM-mountable component */
  {children}
</GlobalHotKeys>

How actions are resolved

How nested key maps are matched

For keymaps defined with components, how close your component is to the element currently focused in the DOM has the greatest affect on how actions are resolved. Whenever a key event occurs (keydown, keypress or keyup), react-hotkeys starts at the component closest to the event's target (the focused element in the browser) and searches up through the hierarchy of focused components, examining each keyMap for actions for which the current key completes the specified combination or sequence.

Regardless of where components appear in the render tree, they are matched with key events after the event has finished propagating through the React app (if the event originated in the React at all). This means if your React app is in focus and it handles a key event, it will be ignored by the components.

The order used for resolving actions and handlers amongst components, is the order in which they mounted (those mounted first, are given the chance to handle an action first). When a component is unmounted, it is removed from consideration. This can get less deterministic over the course of a long session using a React app as components mount and unmount, so it is best to define actions and handlers that are globally unique.

It is recommended to use components whenever possible for better performance and reliability.

You can use the autofocus attributes or programmatically manage focus to automatically focus your React app so the user doesn't have to select it in order for hot keys to take effect. It is common practice to place a component towards the top of your application to match hot keys across your entire React application.

How combinations and sequences are matched

For key combinations, the action only matches if the key is the last one needed to complete the combination. For sequences, the action matches for the last key to complete the last combination in the sequence.

By default, sub-matches are disabled so if you have two actions bound to cmd+a and a, and you press the cmd key and then the a key (without releasing the cmd key), then the cmd+a combination is matched. This allows you to define longer, application-wide key combinations at the top of your app, without them being hidden by shorter context-dependent combinations in different parts of your app. However, it does depend on the order the keys are pressed: in the above example, if a was pressed first and then cmd, the a action would be matched. The trade-off for this behaviour is that combinations are not permitted to overlap: if you have two actions bound to a and b and the user presses a and then b without first releasing a, only the action associated with a will be called (because there are no actions associated with a+b). If you want allow sub-matches, you can use the allowCombinationSubmatches configuration option.

The match occurs on the key event you have specified when defining your keymap (the default is keydown if you have not overridden the defaultKeyEvent configuration option).

Once a matching action is found, react-hotkeys then searches for the corresponding action handler.

How action handlers are resolved

If one of the DOM-mounted descendents of an component are in focus (and it is listening to key events) AND those key events match a hot key in the component's key map, then the corresponding action is triggered.

react-hotkeys starts at the component closest to the event's target (the element that was in focus when the key was pressed) and works its way up through the component tree of focused components, looking for a matching handler for the action. The handler closest to the event target AND a descendant of the component that defines the action (or the component itself), is the one that is called.

That is:

  • Unless one of the DOM-mounted descendents of a component is in focus, the component's actions are not matched
  • Unless a component is nested within the component that defines the action (or is the same component), its handler is not called
  • If a component closer to the event target has defined a handler for the same action, a component's handler won't be called (the closer component's handler will)

A more exhaustive enumeration of react-hotkeys behaviour can be found by reviewing the test suite.

Displaying a list of available hot keys

react-hotkeys provides the getApplicationKeyMap() function for getting a mapping of all actions and key sequences that have been defined by components that are currently mounted.

They are returned as an object, with the action names as keys, and the values are objects describing the key map.

Regardless of which syntax you used to define the keymap, they always appear in the following format:

{
  ACTION_NAME: {
    /**
     * Optional attributes - only present if you defined them
     */
     
    name: 'name',
    group: 'group',
    description: 'description',
    
    /**
     * Attributes always present
     * /
    sequences: [
      {
        action: 'keydown',
        sequence: 'alt+s'
      },
      // ...
    ]
  },
  // ... 
}

Below is how the example application renders a dialog of all available hot keys:

import { getApplicationKeyMap } from 'react-hotkeys';
import React from 'react';

// ...

renderDialog(){
  if (this.state.showDialog) {
    const keyMap = getApplicationKeyMap();

    return (
      <div style={styles.DIALOG}>
        <h2>
          Keyboard shortcuts
        </h2>

        <table>
          <tbody>
          { Object.keys(keyMap).reduce((memo, actionName) => {
              const { sequences, name } = keyMap[actionName];
              
              memo.push(
                <tr key={name || actionName}>
                  <td style={styles.KEYMAP_TABLE_CELL}>
                    { name }
                  </td>
                  <td style={styles.KEYMAP_TABLE_CELL}>
                    { sequences.map(({sequence}) => <span key={sequence}>{sequence}</span>) }
                  </td>
                </tr>
              );
              
              return memo;
            })
           }
          </tbody>
        </table>
      </div>
    );
  }
}

Allowing hotkeys and handlers props to change

For performance reasons, by default react-hotkeys takes the keyMap and handlers prop values when components are focused and when components are mounted. It ignores all subsequent updates to their values when these props change.

If you need the ability to change them while are still in focus, or while are still mounted, then you can pass the allowChanges prop, permitting this behaviour for the particular component.

If you need to do this for all your and components, you can use the ignoreKeymapAndHandlerChangesByDefault option for the Configuration API. This should normally never be done, as it can have significant performance implications.

Ignoring events

By default, all key events that originate from ,