immutable-undo

Immutable Undo

Simple data structure for and undo/redo stack, using ImmutableJS. The structure holds a stack of undo states, and a stack of redo states. It does not keep a reference to the current state to avoid duplicating data if your state is already stored in another structure.

Installation

npm install --save immutable-undo

Reference

Static

History.create

• {Object} [opts] Option object
• {Number} [opts.maxUndos=500] Maximum number of undos stored. Beyond that, the oldest undo is dropped.
• return {History} An empty history

var history = History.create({
    maxUndos: 100
});

Properties

canUndo

• return {Boolean} True if the history has undos

canRedo

• return {Boolean} True if the history has redos

previous

• return {State | Undefined} The most recent state in the undo stack

next

• return {State | Undefined} The most recent state in the redo stack

Methods

push

• {State} newState The state to push on top of the undo stack
• return {History}

Pushes a new state on the undo stack, and clears the redo stack

undo

• {State} current The current state, that will be pushed on the redo stack
• return {History} The history with the undo stack popped once, and the current state added to redos.

redo

• {State} current The current state, that will be pushed on the undo stack
• return {History} The history with the redo stack popped once, and the current state added to redos