HistoryCommand

Documentation / @elitechart/core / HistoryCommand

A reversible command.

redo is the forward action (first invoked when push is called with execute: true). undo reverses it. Both MUST be pure with respect to the command instance — calling redo(); undo(); repeatedly must leave the world in the same state as not calling either.

Example

code

const cmd: HistoryCommand = {
  label: 'Move drawing',
  redo: () => chart.updateDrawing(id, nextState),
  undo: () => chart.updateDrawing(id, prevState),
};
stack.push(cmd);

Properties

kind?

code

readonly optional kind?: string;

Defined in: history/history-stack.ts:32

Command kind for coalescing + filtering (optional).

label

code

readonly label: string;

Defined in: history/history-stack.ts:30

Short, user-readable label used for UI hints (e.g. menu items).

Methods

canMerge()?

code

optional canMerge(prev): boolean;

Defined in: history/history-stack.ts:40

Optional merge test. If canMerge(prev) returns true, the stack coalesces this command into prev via mergeWith and does NOT push a new entry. Useful for rapid drag steps.

Parameters

HistoryCommand

Returns

boolean

mergeWith()?

code

optional mergeWith(prev): HistoryCommand;

Defined in: history/history-stack.ts:45

Optional merge. Extend prev with state from this command; return the merged command (or mutate prev in place and return it).

Parameters

HistoryCommand

Returns

HistoryCommand

redo()

code

redo(): void;

Defined in: history/history-stack.ts:33

Returns

void

undo()

code

undo(): void;

Defined in: history/history-stack.ts:34

Returns

void