Edium Finite State Machine
Overview
Edium FSM is a simple finite state machine written in TypeScript used for gaming or workflow systems. It supports local and global transitions/triggers, entry and exit actions, and the ability to block state transitions before exit. It works both on the client and the server in plain JavaScript or with TypeScript.
Features
- Unlimited number of states
- One or more completed states
- Go to the previous state
- Throws errors on invalid state transitions
- Supports entry actions
- Supports blocking exit actions
- Start on any state
- Reset the state machine with optional restart
- Unlimited local transitions
- Unlimited global transtions/triggers that bypass the current state's transition rules
- State changes occur via triggers
- When creating the machine, optionally send in a context which is sent to all state actions.
Installation
$ npm install @edium/fsmTests/Coverage
The code is fully unit tested with near 100 test percent coverage. Additonally, all code has been vetted using Sonar Scanner (TypeScript) and Code Metrics.
$ npm run test $ npm run coverageExamples
Begin by referencing the module (browser):
;or through Node.js:
const State StateMachine = ;Finally, wire up your state machine and start it:
const entryAction = ( state, context ) => { state.trigger( "next" );}; const exitAction = ( state, context ) => { // Returning false will cancel the state transition return true;}; const decideAction = ( state, context ) => { const index = context.randomize(); if ( index === 0 ) { state.trigger( "gotoThree" ); } else if ( index === 1 ) { state.trigger( "gotoFour" ); }}; const finalAction = ( state ) => { // Can perform some final actions, the state machine is finished running.}; const context = { randomize: () => { return Math.floor( Math.random() * 2 ); }}; const stateMachine = new StateMachine('My first state machine', context);const s1 = stateMachine.createState( "My first state", false, entryAction);const s2 = stateMachine.createState( "My second state", false, decideAction, exitAction); // Trivial use of exit action as an example.const s3 = stateMachine.createState( "My third state", false, entryAction);const s4 = stateMachine.createState( "My fourth state", false, entryAction); // Notice true indicates completed state.var s5 = stateMachine.createState( "My fifth and final state", true, finalAction); // Define all state transitionss1.addTransition( "next", s2 );s2.addTransition( "gotoThree", s3 );s2.addTransition( "gotoFour", s4 );s3.addTransition( "next", s5 );s4.addTransition( "next", s5 ); // Start the state machinestateMachine.start( s1 );