# javascript-state-machine > A finite state machine library Latest version **3.1.0** (published 2018-07-12) · MIT license · 0 weekly downloads ## Install ```sh npm install javascript-state-machine pnpm add javascript-state-machine yarn add javascript-state-machine bun add javascript-state-machine ``` ## Health **Score 23/100 (F)** — status: abandoned. Positive: has types package; no vulnerabilities; high quality score. Warnings: low downloads; no esm support. Negative: abandoned; low maintenance score. ## Facts | | | |---|---| | Version | 3.1.0 | | Published | 2018-07-12 | | First published | 2014-03-16 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | separate (@types/javascript-state-machine) | | Module format | CommonJS | | Dependencies | 0 | | Unpacked size | 88.5 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 8749 | | Author | Jake Gordon | | Maintainers | jakesgordon | | Keywords | finite state machine, state machine, server, client | ## Links - npm: https://www.npmjs.com/package/javascript-state-machine - Repository: https://github.com/jakesgordon/javascript-state-machine - Issues: https://github.com/jakesgordon/javascript-state-machine/issues - npm.io page: https://npm.io/package/javascript-state-machine ## Alternatives - [launchdarkly-js-client-sdk](https://npm.io/package/launchdarkly-js-client-sdk.md) — 2.5M weekly downloads - [@elastic/elasticsearch](https://npm.io/package/@elastic/elasticsearch.md) — 2.1M weekly downloads - [@c8y/client](https://npm.io/package/@c8y/client.md) — 15.3K weekly downloads - [@signaldb/maverickjs](https://npm.io/package/@signaldb/maverickjs.md) — 1.7K weekly downloads - [@bbc/http-transport-cache](https://npm.io/package/@bbc/http-transport-cache.md) — 1.2K weekly downloads ## Recent versions - 3.1.0 (latest) — 2018-07-12 - 3.0.0-rc.1 (next) — 2017-01-10 - 3.0.1 — 2017-06-10 - 2.4.0 — 2016-11-20 - 2.3.5 — 2015-01-21 - 2.3.4 — 2015-01-21 - 2.3.2 — 2014-03-16 - 2.3.1 — 2014-03-16 ## README # Javascript State Machine [![NPM version](https://img.shields.io/npm/v/javascript-state-machine.svg?style=flat)](https://www.npmjs.org/package/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 [jake@codeincomplete.com](mailto:jake@codeincomplete.com), or via my website: [Code inComplete](http://codeincomplete.com/) --- _Source: https://npm.io/package/javascript-state-machine · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._