frontend/js/core.js

import * as HAWS from 'home-assistant-js-websocket';

window.HAWS = HAWS;
window.HASS_DEMO = __DEMO__;
window.HASS_DEV = __DEV__;
window.HASS_BUILD = __BUILD__;
window.HASS_VERSION = __VERSION__;

const init = window.createHassConnection = function (password) {
  const proto = window.location.protocol === 'https:' ? 'wss' : 'ws';
  const url = `${proto}://${window.location.host}/api/websocket?${window.HASS_BUILD}`;
  const options = {
    setupRetry: 10,
  };
  if (password !== undefined) {
    options.authToken = password;
  }

  return HAWS.createConnection(url, options)
    .then(function (conn) {
      HAWS.subscribeEntities(conn);
      HAWS.subscribeConfig(conn);
      return conn;
    });
};

if (window.noAuth === '1') {
  window.hassConnection = init();
} else if (window.localStorage.authToken) {
  window.hassConnection = init(window.localStorage.authToken);
} else {
  window.hassConnection = null;
}

window.addEventListener('error', (e) => {
  const homeAssistant = document.querySelector('home-assistant');
  if (homeAssistant && homeAssistant.hass && homeAssistant.hass.callService) {
    homeAssistant.hass.callService('system_log', 'write', {
      logger: `frontend.${window.HASS_DEV ? 'js_dev' : 'js'}.${window.HASS_BUILD}.${window.HASS_VERSION.replace('.', '')}`,
      message: `${e.filename}:${e.lineno}:${e.colno} ${e.message}`,
    });
  }
});