How to use the highcharts.numberFormat function in highcharts

formatter: function () {
                    return Highcharts.dateFormat('%B %e, %Y', this.x) + '<br>' +
                        this.series.name + ':' + Highcharts.numberFormat(this.y);
                },
            },

formatter: function () {
            return '<b>' + this.series.name + '</b><br>' +
              '<b>' + 'topic:' + that.char_topic + '</b><br>' +
              '<b>' + 'group:' + that.char_groupId + '</b><br>' +
              Highcharts.numberFormat(this.y, 0) + '<br>' +
              Highcharts.dateFormat('%Y-%m-%d %H:%M:%S', this.x) + '<br>';
          }
        },

formatter: function () {
                    return Highcharts.dateFormat('%B %e, %Y', this.x) + '<br>' +
                        this.series.name + ':' + Highcharts.numberFormat(this.y);
                },
            },

formatter: function () {
                    return Highcharts.dateFormat('%B %e, %Y', this.x) + '<br>' +
                        this.series.name + ':' + Highcharts.numberFormat(this.y);
                },
            },

formatter: function () {
                    return Highcharts.dateFormat('%B %e, %Y', this.x) + '<br>' +
                        this.series.name + ':' + Highcharts.numberFormat(this.y);
                },
            },

formatter() {
      const self = this;
      return (
        `<b>${ 
        self.series.name 
        }</b><br>${ 
        Highcharts.dateFormat('%Y-%m-%d %H:%M:%S', self.x) 
        }<br>${ 
        Highcharts.numberFormat(self.y, 2)}`
      );
    },
  },

formatter: function () {
                    return Highcharts.dateFormat('%B %e, %Y', this.x) + '<br>' +
                        this.series.name + ':' + Highcharts.numberFormat(this.y);
                },
            },

formatter: function() {
      return (
        '<b>' +
        this.series.name +
        '</b><br>' +
        Highcharts.dateFormat('%Y-%m-%d %H:%M:%S', this.x) +
        '<br>' +
        Highcharts.numberFormat(this.y, 2)
      );
    },
  },

  'percentage': val => `${Highcharts.numberFormat(val, 2)}%`,
  'money': function(val) { return `$${val}`; }

formatter: function () {
            return '<b>' + this.series.name + '</b><br>' +
                Highcharts.dateFormat('%Y-%m-%d %H:%M:%S', this.x) + '<br>' +
                Highcharts.numberFormat(this.y, 2);
        }
    },