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@initics/tsm

1.0.2 • Public • Published

tsm - Tiny state machine

Manages state transitions and validates transitions before actually changing the state.

Examples

Lets say we want to implement a simple music player, that can be started and stopped.

Possible transitions are:

  • start: ready -> playing
  • stop: playing -> stopped
const { StateMachine } = require('@initics/tsm');
 
// Define the initial state as well as possible transitions
const sm = new StateMachine({
    initial: 'ready',
    transitions: [
        { from: 'ready', to: 'playing' },
        { from: 'playing', to: 'stopped' }
    ]
});
 
console.log('initial state:', sm.state);
 
// start playing
sm.transition('playing');
console.log('start:', sm.state);
 
// stop playing
sm.transition('stopped');
console.log('final state:', sm.state);

Invalid transitions will throw an error:

const { StateMachine } = require('@initics/tsm');
 
const sm = new StateMachine({
    initial: 'ready',
    transitions: [
        { from: 'ready', to: 'playing' },
        { from: 'playing', to: 'stopped' }
    ]
});
 
// throws: Invalid trasition from "ready" to "stopped"
sm.transition('stopped');

Lets implement a more "sophisticated" music player, that can not only be started and stopped, but also paused and resumed.

Possible transitions are:

  • start: ready -> playing
  • pause: playing -> paused
  • stop: playing -> stopped
  • resume: paused -> playing
  • stop: paused -> stopped
const { StateMachine } = require('@initics/tsm');
 
const sm = new StateMachine({
    initial: 'ready',
    transitions: [
        { from: [ 'ready', 'paused' ], to: 'playing' },
        { from: 'playing', to: 'paused' },
        { from: [ 'playing', 'paused' ], to: 'stopped' }
    ]
});
 
console.log('initial state:', sm.state);
 
sm.transition('playing');
console.log('start:', sm.state);
 
sm.transition('paused');
console.log('pause:', sm.state);
 
sm.transition('playing');
console.log('resume:', sm.state);
 
sm.transition('stopped');
console.log('final state:', sm.state);
 

Install

npm i @initics/tsm

DownloadsWeekly Downloads

2

Version

1.0.2

License

MIT

Unpacked Size

23.9 kB

Total Files

32

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