Maquina.js, a javascript Finite State Machine (FSM)

A finite-state machine (FSM) is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number of states at any given time. The FSM can change from one state to another in response to some external inputs; the change from one state to another is called a transition. A FSM is defined by a list of its states, its initial state, and the conditions for each transition. -- Wikipedia

installation

npm install --save maquina-js

basic usage

const StateMachine = require('maquina-js');
const states = ['solid', 'liquid', 'gas', 'plasma'];

  const transitions = [
    { trigger: 'melt', source: 'solid', target: 'liquid' },
    { trigger: 'freeze', source: 'liquid', target: 'solid' },
    { trigger: 'evaporate', source: 'liquid', target: 'gas' },
  ];

  machine = new StateMachine(states, transitions, 'solid');

  machine.getState(); // -> solid
  machine.melt();
  machine.getState(); // -> liquid

adding and removing transitions

After creating your FSM you are still able to add more transitions.

machine.addTransition({ trigger: 'sublimate', source: 'solid', target: 'gas' });
machine.removeTransition('sublimate');

Since it is allowed to have the same transition name for different states, sometimes you will want to specify the state from which you want to remove the transition

machine.removeTransition('sublimate', 'solid');

adding and removing states

machine.addStatete('StateX');
machine.removeState('StateX');

Every time a state is removed from the machine, all tranitions to and from that state are automatically removed.

before and after hooks

function beforeTransition() {
  // pre-transition code
  return true; // or false for preventing the transition from being executed
}

function afterTransition() {
  // post-transition code
  return true;
}

machine.addTransition( { trigger: 'sublimate', source: 'solid', target: 'gas', before: beforeTransition, after: afterTransition } );

Inspired by transitions