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createCommandStack()

createCommandStack(): object

Creates a command stack with undo/redo support.

This stores actions (execute/undo pairs). When you undo, it calls the command's undo function. Use this when you have reversible operations.

For storing states (snapshots) instead of actions, see the Memento pattern's createHistory which stores state snapshots and restores them on undo.

Returns​

Stack with execute, undo, redo, canUndo, canRedo, clear

execute(): (cmd) => void​

Execute a command and push it to the undo stack. Clears redo stack.

cmd: UndoableCommand
Returns: void

undo(): () => boolean​

Undo the last command. Returns false if nothing to undo. Check canUndo first if the result matters to your logic.

Returns: boolean​

redo(): () => boolean​

Redo the last undone command. Returns false if nothing to redo. Check canRedo first if the result matters to your logic.

Returns​

boolean

canUndo​

Get Signature: > *get canUndo*(): boolean​

Returns​

boolean

canRedo​

Get Signature: > *get canRedo*(): boolean​

Returns: boolean​

clear(): () => void​

Clear all history.

Returns: void​

Since​

2.4.0

Example​

let value = 0;
const stack = createCommandStack();

stack.execute(undoable(() => value += 10, () => value -= 10));
stack.execute(undoable(() => value *= 2,  () => value /= 2));
// value = 20

stack.undo(); // value = 10
stack.undo(); // value = 0
stack.redo(); // value = 10