Object-fsm NPM

object-fsm

###Make any JavaScript object to be a finite state machine

Stable, production-ready and battle-tested. Supports NodeJS version 4 and later. Tested up to Node 10.

Installation

npm install object-fsm

How to use

var ObjectFsm = require('object-fsm');

// Any object can become an FSM
var light = {};

// Mix in ObjectFsm to the object
ObjectFsm(light);

light.addStates(['Green', 'Yellow', 'Red']);
light.setStartingState('Red'); // Current state -> Red

// Parameters are: eventName, stateFrom, stateTo, handlerFunc (see doc)
light.addEvent('go', 'Red', 'Green', function () {
    console.log('Let\'s go!');
});

light.addEvent('prepareToStop', 'Green', 'Yellow', function () {
    console.log('Prepare to stop...');
});

light.addEvent('stop', 'Yellow', 'Red', function () {
    console.log('Everybody stop!');
});

light.handleEvent('go'); // state: green
light.handleEvent('prepareToStop'); // state: yellow
light.handleEvent('stop');  // state: red

API Docs

ObjectFsm

Mixes FSM into the object.

Parameters

obj The object that will become an FSM

addState

Adds a state to FSM Note that FSM automatically enters the state added first

Parameters

state string State name

Returns boolean result Whether adding a state succeeded or not

addStates

Adds a list of states to FSM

Parameters

states Array<string>

setStartingState

Sets a starting state. FSM immediately moves to that state.

Parameters

state string

hasState

Returns true if FSM has state {state}

Parameters

state

Returns boolean

hasEvent

Checks if FSM has given event

Parameters

event string

Returns boolean

addEvent

Adds a new event to FSM

Parameters

eventName string Event name
statesFrom (Array<string> | string) A one or more states in which FSM can handle this event
stateTo string State to which the event transitions FSM
handler [function (Any): Any] Function that is invoked upon event

handleEvent

Notifies FSM about an event

Parameters

event string Existing event
arguments ...Any Will be passed to event handler

Returns Any Return value of the event handler

canHandleEvent

Returns true if FSM is able to handle event right now

Parameters

event

Returns boolean

deferTransition

Defers an ongoing transition until future call to finalizeTransition. Use for any asynchronous event hanling. NOTE: this function can be called only in event handler (during an event), or in willTransition event handler.