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redux-undo

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Readme

redux undo/redo

simple undo/redo functionality for redux state containers

Protip: You can use the redux-undo-boilerplate to quickly get started with redux-undo.

Note: When upgrading from 0.3 to 0.4, use .present instead of .currentState.

Installation

npm install --save redux-undo

Making your reducers undoable

redux-undo is a reducer enhancer, it provides the undoable function, which takes an existing reducer and a configuration object and enhances your existing reducer with undo functionality.

Note: If you were accessing state.counter before, you have to access state.counter.present after wrapping your reducer with undoable.

To install, firstly import redux-undo:

// Redux utility functions
import { combineReducers } from 'redux';
// Redux Undo store enhancer
import undoable from 'redux-undo';

Then, add undoable to your reducer(s) like this:

combineReducers({
  counter: undoable(counter)
})

A configuration can be passed like this:

combineReducers({
  counter: undoable(counter, {
    limit: 10 // set a limit for the history
  })
})

Usage

Firstly, import the undo/redo action creators:

import { ActionCreators } from 'redux-undo';

Then, you can use store.dispatch() and the undo/redo action creators to perform undo/redo operations on your state:

store.dispatch(ActionCreators.undo()) // undo the last action
store.dispatch(ActionCreators.redo()) // redo the last action

Configuration

A configuration object can be passed to undoable() like this (values shown are default values):

undoable(reducer, {
  limit: false, // set to a number to turn on a limit for the history

  filter: () => true, // see `Filtering Actions` section

  undoType: ActionTypes.UNDO, // define a custom action type for this undo action
  redoType: ActionTypes.REDO, // define a custom action type for this redo action

  initialState: undefined, // initial state (e.g. for loading)
  initTypes: ['@@redux/INIT', '@@INIT'] // history will be (re)set upon init action type
  initialHistory: { // initial history (e.g. for loading)
    past: [],
    present: config.initialState,
    future: [],
  },

  debug: false, // set to `true` to turn on debugging
})

Filtering Actions

If you don't want to include every action in the undo/redo history, you can pass a function to undoable like this:

undoable(reducer, function filterActions(action, currentState, previousState) {
  return action.type === SOME_ACTION; // only add to history if action is SOME_ACTION
})

// or you could do...

undoable(reducer, function filterState(action, currentState, previousState) {
  return currentState !== previousState; // only add to history if state changed
})

Or you can use the distinctState, ifAction and excludeAction helpers, which should be imported like this:

import undoable, { distinctState, ifAction, excludeAction } from 'redux-undo';

Now you can use the helper, which is pretty simple:

undoable(reducer, { filter: ifAction(SOME_ACTION) })
undoable(reducer, { filter: excludeAction(SOME_ACTION) })

// or you could do...

undoable(reducer, { filter: distinctState() })

... they even support Arrays:

undoable(reducer, { filter: ifAction([SOME_ACTION, SOME_OTHER_ACTION]) })
undoable(reducer, { filter: excludeAction([SOME_ACTION, SOME_OTHER_ACTION]) })

History API

Wrapping your reducer with undoable makes the state look like this:

{
  present: {...currentStateHere...},
  history: {
    past: [...pastStatesHere...],
    present: {...currentStateHere...},
    future: [...futureStatesHere...]
  }
}

Which means you can access all past states (e.g. to show a history) like this: state.history.past

What is this magic? How does it work?

Have a read of the Implementing Undo History recipe in the Redux documents, which explains in detail how redux-undo works.

License

MIT, see LICENSE.md for more information.