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createHistory()

createHistory<T>(initial): History<T>

Creates a history manager for undo/redo functionality.

Tracks state changes as snapshots. Pushing a new state clears any redo history (standard undo/redo behavior).

Type Parameters​

T: T​

The state type

Parameters​

initial: T​

The initial state

Returns: History<T>​

A history manager

Since​

2.4.0

Example​

const history = createHistory({ count: 0 });

history.push({ count: 1 });
history.push({ count: 2 });
history.push({ count: 3 });

history.undo(); // Some({ count: 2 })
history.undo(); // Some({ count: 1 })
history.redo(); // Some({ count: 2 })

// New push clears redo stack
history.push({ count: 10 });
history.canRedo(); // false

Snapshot<T>​

Type

Snapshot<T> = object

A snapshot with metadata.

Since​

2.4.0

Type Parameters​

T: T​

The state type

Properties​

state: T​

timestamp​

readonly timestamp: number

History<T>​

Type

History<T> = object

History manager for undo/redo functionality.

Since​

2.4.0

Type Parameters​

T: T​

The state type

Properties​

current(): () => T​

Returns the current state.

Returns: T​

push(): (state) => void​

Pushes a new state, clearing any redo history.

state: T
Returns: void

undo(): () => Option<T>​

Undoes to previous state. Returns the new current state, or None if at beginning.

Returns: Option<T>​

redo(): () => Option<T>​

Redoes to next state. Returns the new current state, or None if at end.

Returns: Option<T>​

canUndo(): () => boolean​

Returns true if undo is possible.

Returns: boolean​

canRedo(): () => boolean​

Returns true if redo is possible.

Returns: boolean​

history(): () => ReadonlyArray<Snapshot<T>>​

Returns all snapshots in the undo stack (oldest first).

Returns: ReadonlyArray<Snapshot<T>>​

clear(): () => void​

Clears all history, keeping only current state.

Returns​

void