command-stacker v0.3.0

CommandStacker

A lightweight JavaScript utility library to undo and redo commands.

Install

npm install command-stacker

Usage

import CommandStacker from 'command-stacker'

let counter = 0

const incrementCommand = {
  run: () => counter++,
  undo: () => counter--
}

const commandStacker = new CommandStacker()

commandStacker.run(incrementCommand)
// counter = 1

commandStacker.undo()
// counter = 0

commandStacker.redo()
// counter = 1

API

A Command is an object implementing the following interface:

type Command = {
  run: () => void
  undo: () => void
}

The CommandStacker class has two arrays representing the commands it manages: undoStack and redoStack. It has the following methods:

add

Adds a Command to the undoStack and clears the redoStack.

run

Runs a Command, pushes it to the undoStack and clears the redoStack.

undo

Undoes the last command from undoStack, adds it to the redoStack and returns it. If the undoStack is empty, undefined is returned.

redo

Pops the last command from redoStack, adds it to the undoStack and returns it. If the redoStack is empty, undefined is returned.

clear

Clears all commands from undoStack and redoStack.

Generics

It is possible to define your own custom Command type and pass it as a generic argument to CommandStacker:

type CustomCommand = Command & {
  name: string
}

const commandStacker = new CommandStacker<CustomCommand>()

let counter = 0

const incrementCommand = {
  name: 'increment',
  run: counter++,
  undo: counter--
}

commandStacker.run(command)