How to use the fullcalendar.assignTo function in fullcalendar

this.reportError('Specify a googleCalendarApiKey. See http://fullcalendar.io/docs/google_calendar/')
      return null
    }

    // The API expects an ISO8601 datetime with a time and timezone part.
    // Since the calendar's timezone offset isn't always known, request the date in UTC and pad it by a day on each
    // side, guaranteeing we will receive all events in the desired range, albeit a superset.
    // .utc() will set a zone and give it a 00:00:00 time.
    if (!start.hasZone()) {
      start = start.clone().utc().add(-1, 'day')
    }
    if (!end.hasZone()) {
      end = end.clone().utc().add(1, 'day')
    }

    params = assignTo(
      this.ajaxSettings.data || {},
      {
        key: apiKey,
        timeMin: start.format(),
        timeMax: end.format(),
        singleEvents: true,
        maxResults: 9999
      }
    )

    if (timezone && timezone !== 'local') {
      // when sending timezone names to Google, only accepts underscores, not spaces
      params.timeZone = timezone.replace(' ', '_')
    }

    return params

applyMiscProps(rawProps) {
    if (!this.ajaxSettings) {
      this.ajaxSettings = {}
    }
    assignTo(this.ajaxSettings, rawProps)
  }