useHistoryReducer react hook

It's a hook that adds undo and redo functionality to the useReducer.

There is already a few such libraries, but this one is easiest to use. You don't need to modify your existing reducer to use this lib.

Demo

Installation

yarn add react-use-history-reducer

For example, you want to add the history capability to this component:

import React, { useReducer } from 'react'

export const MyComponent = () => {
  const [state, dispatch] = useReducer(reducer, initialState)

  return (
    <div>
      ...
    </div>
  )
}

This is all you need to do:

import React from 'react'
import useHistoryReducer from 'react-use-history-reducer'

export const MyComponent = () => {
  const [state, dispatch, history] = useHistoryReducer(reducer, initialState)

  return (
    <div>
      <button disabled={!history.canUndo} onClick={history.undo}>
        Undo
      </button>
      <button disabled={!history.canRedo} onClick={history.redo}>
        Redo
      </button>
      ...
    </div>
  )
}

Options

You can pass options in a third argument

const [state, dispatch, history, currentHistoryState] = useHistoryReducer(
  reducer,
  initialState,
  {
    omitUnmodified: true,
    useCheckpoints: false,
    max: 5,
    initialHistoryState: initialHistoryState,
  }
)

You can save the currentHistoryState on component unmount and use it later as the initialHistoryState option.

Option	Type	Default	Description
omitUnmodified	boolean	true	If it's true, it doesn't push a new state to the history, if it's the same as a previous one. It compares states using the JSON.stringify
useCheckpoints	boolean	false	Enables checkpoints support. With this option you have to pass historyCheckpoint: true to the action to add state to history
max	number	undefined	Max items length of history
initialHistoryState	HistoryReducerControl	empty state	You can pass here your own initial history state. The current state is available in forth argument returned by useHistoryReducer. It's useful on re-mounting component with useHistoryReducer

The history object

history is a third element in list returned by useHistoryReducer.

const [state, dispatch, history] = useHistoryReducer(reducer, initialState)

It has these properties:

Property	Type	Description
undo	function	Call it to undo
redo	function	Call it to redo
canUndo	boolean	Check if you can undo
canRedo	boolean	Check if you can redo
past	state[]	Past states
future	state[]	Future states
undoRedoCounter	number	Number of undo and redo actions. Can be used if we want to reload some component on undo/redo click

Development

yarn run storybook