frontend/js/common/entity/compute_state_name.js

import computeObjectId from './compute_object_id';

export default function computeStateName(stateObj) {
  if (stateObj._entityDisplay === undefined) {
    stateObj._entityDisplay = (
      stateObj.attributes.friendly_name ||
      computeObjectId(stateObj.entity_id).replace(/_/g, ' '));
  }

  return stateObj._entityDisplay;
}