highcharts 坐标轴 数值 格式化

以Y轴为示例：

yAxis: {
          min: 0,
          gridLineColor: '#ececee',
          gridLineWidth: 1,
          lineColor: '#ececee',
          lineWidth: 1,
          title: {
            align: 'high',
            offset: 0,
            text: this.$t('safetyMonitor.overview.number_of_alarms'),
            rotation: 0,
            y: -10
          },
          labels: {
            enabled: true,
             formatter: function() {
                return Math.round(Math.exp(this.value));
            }
          }
        }