function getTooltipTitle(date) {
            let textTitle = title;
            let formattedDate = formatKey(date);

            if (textTitle.length) {
                if (shouldShowDateInTitle) {
                    textTitle = `${textTitle} - ${formattedDate}`;
                }
            } else {
                textTitle = formattedDate;
            }

            return textTitle;
        }
Gets the tooltipTitle respecting the different settings
@param  {Date | String}  date  Date to use
@private