Javascript State Machine


A library for finite state machines.

!matter state machine

$3

> VERSION 3.0 Is a significant rewrite from earlier versions.
Existing 2.x users should be sure to read the Upgrade Guide.

Installation

In a browser:

``html



`

> after downloading the source or the minified version

Using npm:

`shell
npm install --save-dev @taoqf/javascript-state-machine
`

In Node.js:

`javascript
var StateMachine = require('@taoqf/javascript-state-machine');
`

Usage

A state machine can be constructed using:

`javascript
var fsm = new StateMachine({
init: 'solid',
transitions: [
{ name: 'melt', from: 'solid', to: 'liquid' },
{ name: 'freeze', from: 'liquid', to: 'solid' },
{ name: 'vaporize', from: 'liquid', to: 'gas' },
{ name: 'condense', from: 'gas', to: 'liquid' }
],
methods: {
onMelt: function() { console.log('I melted') },
onFreeze: function() { console.log('I froze') },
onVaporize: function() { console.log('I vaporized') },
onCondense: function() { console.log('I condensed') }
}
});
`

... which creates an object with a current state property:

* fsm.state

... methods to transition to a different state:

* fsm.melt()
* fsm.freeze()
* fsm.vaporize()
* fsm.condense()

... observer methods called automatically during the lifecycle of a transition:

* onMelt()
* onFreeze()
* onVaporize()
* onCondense()

... along with the following helper methods:

* fsm.is(s) - return true if state s is the current state
* fsm.can(t) - return true if transition t can occur from the current state
* fsm.cannot(t) - return true if transition t cannot occur from the current state
* fsm.transitions() - return list of transitions that are allowed from the current state
* fsm.allTransitions() - return list of all possible transitions
* fsm.allStates()` - return list of all possible states

Terminology

A state machine consists of a set of States

* solid
* liquid
* gas

A state machine changes state by using Transitions

* melt
* freeze
* vaporize
* condense

A state machine can perform actions during a transition by observing Lifecycle Events

* onBeforeMelt
* onAfterMelt
* onLeaveSolid
* onEnterLiquid
* ...

A state machine can also have arbitrary Data and Methods.

Multiple instances of a state machine can be created using a State Machine Factory.

Documentation

Read more about

* States and Transitions
* Data and Methods
* Lifecycle Events
* Asynchronous Transitions
* Initialization
* Error Handling
* State History
* Visualization
* State Machine Factory
* Upgrading from 2.x
* TypeScript

Contributing

You can Contribute to this project with issues or pull requests.

You might also want to support this project by purchasing a commercial license.

Release Notes

See RELEASE NOTES file.

License

Dual-licensed under the LGPL for the open source community and also available with support
under a commercial license.

Contact

If you have any ideas, feedback, requests or bug reports, you can reach me at
jake@codeincomplete.com, or via
my website: Code inComplete