in src/visual.ts [304:312]
private getYAxisWidth(chartData: TableHeatMapChartData): number {
let maxLengthText: powerbi.PrimitiveValue = _.maxBy(chartData.categoryY, "length") || "";
maxLengthText = TableHeatMap.textLimit(maxLengthText.toString(), this.settings.yAxisLabels.maxTextSymbol);
return TextMeasurementService.measureSvgTextWidth({
fontSize: PixelConverter.toString(this.settings.yAxisLabels.fontSize),
text: maxLengthText.trim(),
fontFamily: this.settings.yAxisLabels.fontFamily
}) + TableHeatMap.YAxisAdditinalMargin;
}