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https://github.com/jakesgordon/javascript-state-machine

A javascript finite state machine library
https://github.com/jakesgordon/javascript-state-machine

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A javascript finite state machine library

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# Javascript State Machine

[![NPM version](https://badge.fury.io/js/javascript-state-machine.svg)](https://badge.fury.io/js/javascript-state-machine)
[![Build Status](https://travis-ci.org/jakesgordon/javascript-state-machine.svg?branch=master)](https://travis-ci.org/jakesgordon/javascript-state-machine)

A library for finite state machines.

![matter state machine](examples/matter.png)


### NOTE for existing users

> **VERSION 3.0** Is a significant rewrite from earlier versions.
Existing 2.x users should be sure to read the [Upgrade Guide](docs/upgrading-from-v2.md).


# Installation

In a browser:

```html

```

> after downloading the [source](dist/state-machine.js) or the [minified version](dist/state-machine.min.js)

Using npm:

```shell
npm install --save-dev javascript-state-machine
```

In Node.js:

```javascript
var StateMachine = require('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**](docs/states-and-transitions.md)

* solid
* liquid
* gas

A state machine changes state by using [**Transitions**](docs/states-and-transitions.md)

* melt
* freeze
* vaporize
* condense

A state machine can perform actions during a transition by observing [**Lifecycle Events**](docs/lifecycle-events.md)

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

A state machine can also have arbitrary [**Data and Methods**](docs/data-and-methods.md).

Multiple instances of a state machine can be created using a [**State Machine Factory**](docs/state-machine-factory.md).

# Documentation

Read more about

* [States and Transitions](docs/states-and-transitions.md)
* [Data and Methods](docs/data-and-methods.md)
* [Lifecycle Events](docs/lifecycle-events.md)
* [Asynchronous Transitions](docs/async-transitions.md)
* [Initialization](docs/initialization.md)
* [Error Handling](docs/error-handling.md)
* [State History](docs/state-history.md)
* [Visualization](docs/visualization.md)
* [State Machine Factory](docs/state-machine-factory.md)
* [Upgrading from 2.x](docs/upgrading-from-v2.md)

# Contributing

You can [Contribute](docs/contributing.md) to this project with issues or pull requests.

# Release Notes

See [RELEASE NOTES](RELEASE_NOTES.md) file.

# License

See [MIT LICENSE](https://github.com/jakesgordon/javascript-state-machine/blob/master/LICENSE) file.

# Contact

If you have any ideas, feedback, requests or bug reports, you can reach me at
[[email protected]](mailto:[email protected]), or via
my website: [Code inComplete](http://codeincomplete.com/)