immer-undo v0.1.0

Revert any number of immer patches.

 

revertPatch(base, patch)

Mutate the given object/array by reversing the given patch.

Errors are thrown when patches are reverted in the wrong order.

import { Patch } from 'immer'
import { revertPatch } from 'immer-undo'

// Revert a single patch
let state = revertPatch(
  { a: 1 },
  {
    op: 'remove',
    path: ['b'],
    origValue: 1,
  }
)
state.b == 1 // => true

// Revert all patches using `reduceRight`
let history: Patch[] = [
  { op: 'add', path: ['a'], value: 1 },
  { op: 'replace', path: ['a'], value: 2, origValue: 1 },
]
state = history.reduceRight(revertPatch, { a: 2 })
'a' in state // => false

 

createPatchHistory(history)

Creates an undo/redo function pair for managing patch history.

import { createPatchHistory } from 'immer-undo'

let { history, undo, redo } = createPatchHistory()
history.push({ op: 'add', path: ['a'], value: 1 })

let state = { a: 1 }
state = undo(state)
'a' in state // => false

state = redo(state)
state.a == 1 // => true

Tip: Pass a number to undo/redo to undo/redo many patches at once.

 

generateInversePatch(patch)

Generate a new patch that's the exact opposite of the given patch.

import { generateInversePatch } from 'immer-undo'

let patch = generateInversePatch({ op: 'add', path: ['a'], value: 1 })
patch.op == 'remove'
patch.path[0] == 'a'
patch.origValue == 1