home-assistant-js-websocket

:aerial_tramway: JavaScript websocket client for Home Assistant

This is a websocket client written in JavaScript that communicates with the Home Assistant websocket API. It can be used to integrate Home Assistant into your apps. It has 0 dependencies.

import { createConnection, subscribeEntities } from 'home-assistant-js-websocket';

function stateChanged(event) {
  console.log('state changed', event);
}

createConnection('ws://localhost:8123/api/websocket').then(
  (conn) => {
    console.log('Connection established!');
    subscribeEntities(conn, entities => console.log('New entities!', entities));
  },
  err => console.error('Connection failed with code', err)
)

Try it on JSFiddle.

Usage

Initializing connection

Connections to the websocket API are initiated by calling createConnection(url[, options]). createConnection will return a promise that will resolve to either a Connection object or rejects with an error code.

Available options

Currently the following options are available:

Option	Description
authToken	Legacy auth token to use to validate with Home Assistant.
accessToken	OAuth 2 access token to use to validate with Home Assistant.
expires	Access token will expires on.
setupRetry	Number of times to retry initial connection when it fails. -1 means infinite.

Possible error codes

Currently the following error codes can be expected:

Error	Description
ERR_CANNOT_CONNECT	If the client was unable to connect to the websocket API.
ERR_INVALID_AUTH	If the supplied authentication was invalid.

You can import them into your code as follows:

import { ERR_CANNOT_CONNECT, ERR_INVALID_AUTH } from 'home-assistant-js-websocket';

Automatic reconnecting

The connection object will automatically try to reconnect to the server when the connection gets lost. On reconnect, it will automatically resubscribe the event listeners.

The Connection object implements three events related to the reconnecting logic.

Event	Data	Description
ready	-	Fired when authentication is successful and the connection is ready to take commands.
disconnected	-	Fired when the connection is lost.
reconnect-error	Error code	Fired when we encounter a fatal error when trying to reconnect. Currently limited to ERR_INVALID_AUTH.

You can attach and remove listeners as follows:

function eventHandler(connection, data) {
  console.log('Connection has been established again');
}

conn.addEventListener('ready', eventHandler);
conn.removeEventListener('ready', eventHandler);

Entities

You can subscribe to the entities of Home Assistant. Your callback will be called when the entities are first loaded and on every change to the state of any of the entities after that. The callback will be called with a single object that contains the entities keyed by entity_id.

The function subscribeEntities will return a promise that resolves to an unsubscribe function.

import { subscribeEntities } from 'home-assistant-js-websocket';

// conn is the connection from earlier.

subscribeEntities(conn, entities => console.log('New entities!', entities));

Config

You can subscribe to the config of Home Assistant. Config can change when either a component gets loaded or a new service gets registered.

The function subscribeConfig will return a promise that resolves to an unsubscribe function.

import { subscribeConfig } from 'home-assistant-js-websocket';

// conn is the connection from earlier.

subscribeConfig(conn, config => console.log('New config!', config));

Connection API Reference

conn.getStates()

Get the state of all entities. Returns a promise that will resolve to the result of querying the server for all the states.

conn.getServices()

Get all available services. Returns a promise that will resolve to the result of querying the server for all the services.

conn.getConfig()

Get the Home Assistant server config. Returns a promise that will resolve to the result of querying the server for all the config.

conn.callService(domain, service[, serviceData])

Call a service within Home Assistant. Returns a promise that will resolve when the service has been called successfully.

conn.subscribeEvents(eventCallback[, eventType])

Subscribe to all or specific events on the Home Assistant bus. Calls eventCallback for each event that gets received.

Returns a promise that will resolve to a function that will cancel the subscription once called.

conn.addEventListener(eventType, listener)

Listen for events on the connection. See docs.

Using this in NodeJS

To use this package in NodeJS, install the ws package and make it available as WebSocket on the global object before importing this package.

const WebSocket = require('ws');
global.WebSocket = WebSocket;
const HAWS = require("home-assistant-js-websocket");

const getWsUrl = haUrl => `ws://${haUrl}/api/websocket`;

HAWS.createConnection(getWsUrl('localhost:8123')).then(conn => {
  HAWS.subscribeEntities(conn, logEntities);
});

function logEntities(entities) {
  Object.keys(entities).forEach(key => console.log(`${key}: ${entities[key].state}`));
  console.log('')
}