How to use the moment-timezone/moment-timezone function in moment-timezone

let dateSetting = ((typeof date !== 'string') || (date.indexOf('moment(') === -1)) ? moment(date) : null;
  if (dateSetting && dateSetting.isValid()) {
    return dateSetting.toDate();
  }

  dateSetting = null;
  try {
    const value = Evaluator.evaluator(`return ${date};`, 'moment')(moment);
    if (typeof value === 'string') {
      dateSetting = moment(value);
    }
    else if (typeof value.toDate === 'function') {
      dateSetting = moment(value.toDate().toUTCString());
    }
    else if (value instanceof Date) {
      dateSetting = moment(value);
    }
  }
  catch (e) {
    return null;
  }

  if (!dateSetting) {
    return null;
  }

  // Ensure this is a date.
  if (!dateSetting.isValid()) {
    return null;
  }

  return dateSetting.toDate();

export function formatDate(value, format, timezone) {
  const momentDate = moment(value);
  if (timezone === currentTimezone()) {
    // See if our format contains a "z" timezone character.
    if (format.match(/\s(z$|z\s)/)) {
      loadZones();
      if (moment.zonesLoaded) {
        return momentDate.tz(timezone).format(convertFormatToMoment(format));
      }
      else {
        return momentDate.format(convertFormatToMoment(format.replace(/\s(z$|z\s)/, '')));
      }
    }

    // Return the standard format.
    return momentDate.format(convertFormatToMoment(format));
  }
  if (timezone === 'UTC') {

return date.isValid() ? date.toDate() : null;
  }

  let dateSetting = ((typeof date !== 'string') || (date.indexOf('moment(') === -1)) ? moment(date) : null;
  if (dateSetting && dateSetting.isValid()) {
    return dateSetting.toDate();
  }

  dateSetting = null;
  try {
    const value = Evaluator.evaluator(`return ${date};`, 'moment')(moment);
    if (typeof value === 'string') {
      dateSetting = moment(value);
    }
    else if (typeof value.toDate === 'function') {
      dateSetting = moment(value.toDate().toUTCString());
    }
    else if (value instanceof Date) {
      dateSetting = moment(value);
    }
  }
  catch (e) {
    return null;
  }

  if (!dateSetting) {
    return null;
  }

  // Ensure this is a date.
  if (!dateSetting.isValid()) {
    return null;

if (format.match(/\s(z$|z\s)/)) {
      loadZones();
      if (moment.zonesLoaded) {
        return momentDate.tz(timezone).format(convertFormatToMoment(format));
      }
      else {
        return momentDate.format(convertFormatToMoment(format.replace(/\s(z$|z\s)/, '')));
      }
    }

    // Return the standard format.
    return momentDate.format(convertFormatToMoment(format));
  }
  if (timezone === 'UTC') {
    const offset = offsetDate(momentDate.toDate(), 'UTC');
    return `${moment(offset.date).format(convertFormatToMoment(format))} UTC`;
  }

  // Load the zones since we need timezone information.
  loadZones();
  if (moment.zonesLoaded) {
    return momentDate.tz(timezone).format(`${convertFormatToMoment(format)} z`);
  }
  else {
    return momentDate.format(convertFormatToMoment(format));
  }
}

jsonLogic.add_operation('relativeMaxDate', (relativeMaxDate) => {
  return moment().add(relativeMaxDate, 'days').toISOString();
});

export function offsetDate(date, timezone) {
  if (timezone === 'UTC') {
    return {
      date: new Date(date.getTime() + (date.getTimezoneOffset() * 60000)),
      abbr: 'UTC'
    };
  }
  const dateMoment = moment(date).tz(timezone);
  return {
    date: new Date(date.getTime() + ((dateMoment.utcOffset() + date.getTimezoneOffset()) * 60000)),
    abbr: dateMoment.format('z')
  };
}

jsonLogic.add_operation('getDate', (date) => {
  return moment(date).toISOString();
});

export function momentDate(value, format, timezone) {
  const momentDate = moment(value);
  if (timezone === 'UTC') {
    timezone = 'Etc/UTC';
  }
  if ((timezone !== currentTimezone() || (format && format.match(/\s(z$|z\s)/))) && moment.zonesLoaded) {
    return momentDate.tz(timezone);
  }
  return momentDate;
}

export function getDateSetting(date) {
  if (_.isNil(date) || _.isNaN(date) || date === '') {
    return null;
  }

  if (date instanceof Date) {
    return date;
  }
  else if (typeof date.toDate === 'function') {
    return date.isValid() ? date.toDate() : null;
  }

  let dateSetting = ((typeof date !== 'string') || (date.indexOf('moment(') === -1)) ? moment(date) : null;
  if (dateSetting && dateSetting.isValid()) {
    return dateSetting.toDate();
  }

  dateSetting = null;
  try {
    const value = Evaluator.evaluator(`return ${date};`, 'moment')(moment);
    if (typeof value === 'string') {
      dateSetting = moment(value);
    }
    else if (typeof value.toDate === 'function') {
      dateSetting = moment(value.toDate().toUTCString());
    }
    else if (value instanceof Date) {
      dateSetting = moment(value);
    }

jsonLogic.add_operation('relativeMinDate', (relativeMinDate) => {
  return moment().subtract(relativeMinDate, 'days').toISOString();
});