@xstate/fsm

_{XState for Finite State Machines}

This package contains a minimal, 1kb implementation of XState for finite state machines.

• Read the full documentation in the XState docs.
• Read our contribution guidelines.

Features

	@xstate/fsm	XState
Finite states	✅	✅
Initial state	✅	✅
Transitions (object)	✅	✅
Transitions (string target)	✅	✅
Delayed transitions	❌	✅
Eventless transitions	❌	✅
Wildcard transitions	✅	✅
Nested states	❌	✅
Parallel states	❌	✅
History states	❌	✅
Final states	❌	✅
Context	✅	✅
Entry actions	✅	✅
Exit actions	✅	✅
Transition actions	✅	✅
Parameterized actions	❌	✅
Transition guards	✅	✅
Parameterized guards	❌	✅
Spawned actors	❌	✅
Invoked actors	❌	✅

• Finite states (non-nested)
• Initial state
• Transitions (object or strings)
• Context
• Entry actions
• Exit actions
• Transition actions
• state.changed

If you want to use statechart features such as nested states, parallel states, history states, activities, invoked services, delayed transitions, transient transitions, etc. please use XState.

Quick start

Installation

npm i @xstate/fsm

Usage (machine)

import { createMachine } from '@xstate/fsm';

const toggleMachine = createMachine({
  id: 'toggle',
  initial: 'inactive',
  states: {
    inactive: { on: { TOGGLE: 'active' } },
    active: { on: { TOGGLE: 'inactive' } }
  }
});

const { initialState } = toggleMachine;

const toggledState = toggleMachine.transition(initialState, 'TOGGLE');
toggledState.value;
const untoggledState = toggleMachine.transition(toggledState, 'TOGGLE');
untoggledState.value;
// => 'inactive'

Usage (service)

import { createMachine, interpret } from '@xstate/fsm';

const toggleMachine = createMachine({});

const toggleService = interpret(toggleMachine).start();

toggleService.subscribe((state) => {
  console.log(state.value);
});

toggleService.send('TOGGLE');
toggleService.send('TOGGLE');
toggleService.stop();