How can I use the locale service provided by Angular to set the tooltip label in Chart.js when using the tooltip call function?

    const config: any = {
      type: 'bar',
      data: {
        localNumberPipe : this.localNumberPipe,
        labels: this.labels,
        datasets: [{
          minBarLength: 5,
          maxBarThickness: 50,
          label: 'Waterfall Chart',
          elements: {
            bar: {
              backgroundColor: this.color,
              borderColor: this.color,
            }
          },
          data: this.data,
          borderWidth: 1,
          borderSkipped: false
        }]
      },
      options: {
        maintainAspectRatio: false,
        plugins: {
          tooltip: {
            callbacks: {
              context: {
                _this: this,
              },
              label: function (context) {
                var bar = JSON.parse(context.formattedValue);
                var label = [];
                if (bar) {
                  var l=  this.locale;
                  const diff = Number.parseFloat(bar[1]) - Number.parseFloat(bar[0]);
                  label.push('Difference: ' + formatNumber(diff, 'en-US', '1.0-0'));
                  label.push('Start: ' + formatNumber(bar[0], 'en-US', '1.0-0'));
                  label.push('End: ' + formatNumber(bar[1], 'en-US', '1.0-0'));
                }
                return label;
              }
            }
          }
        },
        scales: {
          y: {
            beginAtZero: true
          }
        }
      },
      plugins: [connectorLines]
    };

In the constructor I have this code where I am getting localy as ‘an-US’

  constructor(private localeService: LocaleService) {
    this.localNumberPipe = new LocalNumberPipe(localeService);
    Chart.register(...registerables);
     **this.locale** = this.localeService.locale ;
    console.log(this.locale);
  }

but if I try to access this.locale in tooltip callback function it returns undefine. Is it something related to this scope? if so is any way to add locale in chart config as a property so I can access it in tooltip callback function.

In the developer console this return the tooltip details.

 label: function (context) {
                var bar = JSON.parse(context.formattedValue);
                debugger /// execute this at this stage  

enter image description here

Thank you for your support!