fsm-event

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Stateful finite state machine wrapper around
fsm. Emits events when transitioning
states.

Installation

``bash
$ npm install fsm-event
`

Usage

`js
const fsm = require('fsm-event')

const m = fsm('START', {
START: { pause: 'PAUSED' },
PAUSED: { resume: 'START' }
})

m.on('START:leave', cb => console.log('leaving start!'); cb())
m.on('PAUSED', () => console.log('paused state!'))

m('pause')
// 'leaving start'
// 'paused state!'
`

API

$3

Create a state machine. start defaults to START.

$3

Attach a listener to the state machine. See events for an overview
of all events.

$3

Transition states in the state machine. Must be a valid transition defined on
initalization. Will throw if an invalid transition is triggered. Alias:
m.emit(event).

Events

Each state transition triggers 3 events. __important:__ When listening to
:enter or :leave events, the callback must be called so that the state
machine can proceed to the next state.
`txt
error incorrect transition
when new state is entered
:enter when transitioning into state
:leave when transitioning away from state
done when state transition finished
``

Why?

Most state machines have overly complicated interfaces for managing state. The
fsm state machine is simple but doesn't manage state for you, so I wrote a
wrapper around it that manages state in an event-driven way. The initial use
case was to manage complex, stateful UI elements but it can be used anywhere.

See Also

- fsm
- javascript-state-machine
- statement
- stream-fsm

License

MIT

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