home-assistant-javascript-templates

A JavaScript utility to render Home Assistant JavaScript templates.

Install

npm

npm install home-assistant-javascript-templates

yarn

yarn add home-assistant-javascript-templates

PNPM

pnpm add home-assistant-javascript-templates

Basic Usage

Usage with commonJS

const HomeAssistantJavaScriptTemplates = require('home-assistant-javascript-templates');

const haJsTemplates = new HomeAssistantJavaScriptTemplates(
    document.querySelector('home-assistant')
);

haJsTemplates.getRenderer()
    then((renderer) => {
        renderer.renderTemplate('... template string ...');
        renderer.trackTemplate('... template string ...', () => {
            // execute this function every time that en entity used in the template changes
        });
    });

Usage with ES6 modules

import HomeAssistantJavaScriptTemplates from 'home-assistant-javascript-templates';

const haJsTemplates = new HomeAssistantJavaScriptTemplates(
    document.querySelector('home-assistant')
);

haJsTemplates.getRenderer()
    then((renderer) => {
        renderer.renderTemplate('... template string ...');
        renderer.trackTemplate('... template string ...', () => {
            // execute this function every time that en entity used in the template changes
        });
    });

API

The package exposes a class that needs to be instantiated and the resolved promise that returns the getRenderer method of this instance is what you need to use in your code to render JavaScript templates.

HomeAssistantJavaScriptTemplates class

Main class of the library, it is the default export in the package.

new HomeAssistantJavaScriptTemplates(
    ha,
    options
);

Parameter	Optional	Description
ha	no	An HTML element that has the hass object as a property (e.g. the home-assistant custom element).
options	yes	An object containing the configuration options.

Configuration options

Parameter	Optional	Default	Description
throwErrors	yes	false	Indicates if the library should throw if the template contains any error. If not, it will log the errors as a warning in the console and return undefined instead.
throwWarnings	yes	true	Indicates if the library should throw warnings in the console, either when there is an error in the templates and throwErrors is configured in false, or when a non-existent entity or domain is used in the templates.
variables	yes	{}	An object holding custom variables to be used inside the templates. The values could be any type

Methods

getRenderer

Returns a Promise than once it resolved returns an instance of the HomeAssistantJavaScriptTemplatesRenderer class.

HomeAssistantJavaScriptTemplatesRenderer class

This class is only exported as a type in the package, you cannot import it directly. An instance of this class will be returned by the promise that is returned by the getRenderer method of the HomeAssistantJavaScriptTemplates class.

Properties

variables

This property gets and sets the global variables that will be available in the templates.

Methods

renderTemplate

renderTemplate(template: string): any

This method renders a JavaScript template and return its result. It needs a string as a parameter. Inside this string you can use several objects and methods. It returns whatever the JavaScript code returns, because of that it is typed as any.

trackTemplate

trackTemplate(
    template: string,
    renderingFunction: (result?: any) => void
): () => void

This method registers a template tracking. It executes the renderingFunction sent to the method with the result of the rendered template and will execute renderingFunction with an updated result of the rendered template every time that the entities used in the template update. You can use several objects and methods inside the template string.

If some entity was not reached in the template code because it was inside a condition that never met, then it will not be tracked, so if its state changes it will not trigger the renderingFunction again. Only those entities that were called during the rendering using states, is_state, state_attr, is_state_attr, has_value entities, entity_prop, is_entity_prop or device_id will be included.

This method will return a function. When this function is executed, the tracking of that template/rendering function is removed and subsecuent changes in the entities of the template will not call the renderingFunction.

cleanTracked

cleanTracked(entityId?: string): void

This method will clean the template tracking for a specific entity or will clean all the template trackings if no entity id is specified.

Objects and methods available in the templates

hass

The hass object

states

states could be used in two ways, as a function or as an object. When using it as function it only allows an entity id (containing the domain) as a parameter and it will return the state of that entity. As an object it allows you to access a domain or the full entity state object.

Note: If you try to use states as a function sending a domain it will throw an error.

// Using states as a function
states('device_tracker.paulus') // returns the state of the entity id 'device_tracker.paulus'

// Using states as an object
states['device_tracker.paulus'].state // returns the state of the entity id 'device_tracker.paulus'
states.device_tracker.paulus.state // returns the state of the entity id 'device_tracker.paulus'
states.device_tracker // returns an object containing all the entities states of the 'device_tracker' domain

Note: Avoid using states['device_tracker.paulus'].state or states.device_tracker.paulus.state, instead use states('device_tracker.paulus') which will return undefined if the device id doesn‘t exist or the entity isn’t ready yet (the former will throw an error). If you still want to use them it is advisable to use the Optional chaining operator, e.g. states['device_tracker.paulus']?.state or states.device_tracker?.paulus?.state.

is_state

Method to check if the state of an entity is equal to a certain value. It returns a boolean. If the entity id doesn‘t exist it returns false.

is_state('device_tracker.paulus', 'not_home')

state_attr

Method to return the value of the state attribute or undefined if it doesn’t exist.

state_attr('device_tracker.paulus', 'battery')

is_state_attr

Method to test if the given entity attribute is the specified state. It returns a boolean, if the entity doesn‘t exist it returns false.

is_state_attr('device_tracker.paulus', 'battery', 40)

has_value

Method to test if the given entity is not unknown or unavailable. It returns a boolean, if the entity doesn‘t exist it returns false.

has_value('sensor.my_sensor')

entities

entities could be used in two ways, as a function or as an object.

// Using entities as a function
entities() // return all the entities
entities('device_tracker') // returns an object containing all the entities of the 'device_tracker' domain
entities('device_tracker.paulus') // returns the entity 'device_tracker.paulus'

// Using entities as an object
entities.device_tracker // returns an object containing all the entities of the 'device_tracker' domain
entities['device_tracker.paulus'] // returns the entity 'device_tracker.paulus'
entities.device_tracker.paulus // returns the entity 'device_tracker.paulus'

entity_prop

Method that returns the value of a property of an entity or undefined if it doesn’t exist.

entity_prop('device_tracker.paulus', 'platform')

is_entity_prop

Method to test if the value of an entity property matches a value. It returns a boolean, if the entity id or the property don‘t exist it returns false.

is_entity_prop('device_tracker.paulus', 'platform', 'hacs')

devices

devices could be used in two ways, as a function or as an object.

// Using devices as a function
devices() // returns all the devices
devices('706ad0ebe27e105d7cd0b73386deefdd') // returns the device that matches the device id

// Using devices as an object
devices['706ad0ebe27e105d7cd0b73386deefdd'] // returns the device that matches the device id

device_attr

Method that returns the value of an attribute for the given device id or undefined if it doesn’t exist.

device_attr('706ad0ebe27e105d7cd0b73386deefdd', 'manufacturer')

is_device_attr

Method to test if the value of a device attribute matches a value. It returns a boolean, if the device id doen‘t exist it returns false.

is_device_attr('706ad0ebe27e105d7cd0b73386deefdd', 'manufacturer', 'Synology')

device_id

Method to return the device id for a given entity id or undefined if the entity doesn‘t exist.

device_id('sensor.my_sensor')

areas

Method to return an array with all the areas ids.

areas()

area_id

Method to return the area id for a given device id, entity id, or area name. It returns undefined if the area doesn‘t exist.

area_id('b8c1c9dd23cb82bbfa09b5657f41d04f')
area_id('sensor.my_sensor')
area_id('Woonkamer')

area_name

Method to return the area name for a given device id, entity id, or area id. It returns undefined if the area doesn‘t exist.

area_name('b8c1c9dd23cb82bbfa09b5657f41d04f')
area_name('sensor.my_sensor')
area_name('woonkamer')

area_entities

Method to return an array of entity ids tied to a given area id or area name. If the area doesn‘t exist it returns an empty array.

area_entities('woonkamer')
area_entities('Woonkamer')

area_devices

Method to return an array of device ids tied to a given area id or area name. If the area doesn‘t exist it returns an empty array.

area_devices('woonkamer')
area_devices('Woonkamer')

user_name

Property to return the name of the user logged in in Home Assistant. It returns a string.

user_name

user_is_admin

Property to return if the user logged in in Home Assistant is admin or not. It returns a boolean.

user_is_admin

user_is_owner

Property to return if the user logged in in Home Assistant is the owner. It returns a boolean.

user_is_owner

user_agent

Property to return the user agent of the browser in which Home Assistant is running.

user_agent

panel_url

Property to return the current Home Assistant panel URL (window.location.pathname).

panel_url

Examples

Get a device attribute and return a formatted text with it

import HomeAssistantJavaScriptTemplates  from 'home-assistant-javascript-templates';

const haJsTemplates = new HomeAssistantJavaScriptTemplates(
    document.querySelector('home-assistant')
);

/**
 * Get the device id of an entity
 * With the device id get an attribute of the device
 * Return the value of the attribute prefixed with "sn: "
 * It will return something like "sn: 123456"
 */
haJsTemplates.getRenderer()
    .then((renderer) => {
        const result = renderer.renderTemplate(`
            const deviceId = device_id("binary_sensor.koffiezetapparaat_aan");
            const serialNumber = device_attr(deviceId, "serial_number");
            return "sn:" + serialNumber;
        `);
        console.log(result);
    });

Get all the available updates and update an HTML element with the result with entity changes

import HomeAssistantJavaScriptTemplates  from 'home-assistant-javascript-templates';

const haJsTemplates = new HomeAssistantJavaScriptTemplates(
    document.querySelector('home-assistant'),
    {
        variables: {
            PREFIX: 'Updates:'
        }
    }
);

haJsTemplates.getRenderer()
    .then((renderer) => {
        const element = document.querySelector('#my-element');
        const untrack = renderer.trackTemplate(
            `
            const udatesEntities = states.update;
            const updateEntitiesValues = Object.values(udatesEntities);
            const updatesEntitiesOn = updateEntitiesValues.filter((entity) => entity.state === 'on');
            return `${PREFIX} ${updatesEntitiesOn.length}`;
            `,
            (result) => {
                element.innerHTML = result;
            }
        );

        // Later untrack the template
        untrack();

    });