undo-history

Undo and redo as a value: a pure history of any document, with bursts (a drag is one entry), redo that drops on a new change, and a depth limit


pnpm dlx shadcn@latest add @audio-ui/undo-history

import { HISTORY_LIMIT, emptyHistory, canUndo, canRedo, beginChange, /* … */ } from "@/lib/undo-history";

Files	`lib/undo-history.ts`
Depends on	Nothing
npm	Nothing
Used by	`history`, `use-arrangement`, `use-undo-history`

Export	Kind	What it is
`History`	interface	Undo and redo as a value: every function takes the present and hands back the present, and holds no state of its own.
`HistoryStep`	interface
`HISTORY_LIMIT`	const	How many entries a history keeps: deep, not infinite.
`emptyHistory`	function
`canUndo`	function
`canRedo`	function
`beginChange`	function	Opens a burst, or joins the one already open.
`settleChange`	function	Closes a burst: everything it did becomes one entry on `past`.
`recordChange`	function	A change made in one go: a burst opened and closed.
`undo`	function	Takes back the latest change, or returns null when there is none.
`redo`	function	Puts back what undo took, or returns null when there is nothing to put back.

Usage

Undo and redo of any value, as a value: the steps behind it and after it, a gesture recorded as one step, and the last 100 kept.

import { canUndo, emptyHistory, recordChange, redo, undo } from "@/lib/undo-history";

let history = emptyHistory<Note[]>();
history = recordChange(history, notesBefore); // before an edit
const step = undo(history, notesNow); // { history, present } to go back to, null with nothing to undo

beginChange and settleChange make a drag one step. In React, useUndoHistory holds it for you; the arrangement's undo is built on it.

audio-export sortable-drag

Built by Ouest Labs, the source code is available on GitHub.

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