CommandStacker


A lightweight JavaScript utility library to undo and redo commands.

Install

``
npm install command-stacker
`

Usage

`typescript
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:

`typescript
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:

$3

Adds a Command to the undoStack and clears the redoStack.

$3

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

$3

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

$3

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

$3

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:

`typescript
type CustomCommand = Command & {
name: string
}

const commandStacker = new CommandStacker()

let counter = 0

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

commandStacker.run(command)
``