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chore: move to Intl.NumberFormat for formatting numbers #120

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76666d2
chore: move to Intl.NumberFormat for formatting numbers
Pixselve Nov 3, 2025
f31ef11
test: update number formatting precision in cartesian chart test
Pixselve Nov 5, 2025
c80f811
feat: adds a `locale` prop
Pixselve Nov 24, 2025
97707e4
Merge remote-tracking branch 'origin/main' into number-formatting
Pixselve Jan 7, 2026
498af9a
chore: use locale utility + tweak formatter
Pixselve Jan 7, 2026
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34 changes: 16 additions & 18 deletions pages/common/formatters.ts
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Expand Up @@ -17,36 +17,34 @@ export function dateFormatter(value: null | number) {
.join("\n");
}

export function numberFormatter(value: null | number) {
/**
* @see https://www.unicode.org/cldr/cldr-aux/charts/29/verify/numbers/en.html
*/
export function numberFormatter(value: number | null, locale: string = "en-US"): string {
if (value === null) {
return "";
}

const format = (num: number) => parseFloat(num.toFixed(2)).toString(); // trims unnecessary decimals

const absValue = Math.abs(value);

if (absValue === 0) {
return "0";
}

if (absValue < 0.01) {
return value.toExponential(0);
}

if (absValue >= 1e9) {
return format(value / 1e9) + "G";
}

if (absValue >= 1e6) {
return format(value / 1e6) + "M";
}

if (absValue >= 1e3) {
return format(value / 1e3) + "K";
// Use scientific notation for very small numbers
if (absValue < 1e-9) {
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@jperals jperals Nov 4, 2025

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Is there a specific reason why the threshold of this condition changes from 0.01 (i.e, 1e-2) to 1e-9?

@pan-kot Would this be a problem?

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@Pixselve Pixselve Nov 4, 2025

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In this PR, I also updated how numbers are truncated, to reflect how CloudWatch charts are currently behaving. The number 0.00086661402 is truncated in CDS, but not on the console.

I am open to the discussion about that. It may be valuable to expose that setting to the chart props?

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@pan-kot pan-kot Nov 12, 2025 •
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You can do that in the test pages - but let's not change the current precision in the default chart formatters. What is good for one team might not work for another.

All formatters can be already overridden in both public and core APIs.

return new Intl.NumberFormat(locale, {
notation: "scientific",
maximumFractionDigits: 2,
}).format(value);
}

return format(value);
// Use compact notation for normal range
return new Intl.NumberFormat(locale, {
notation: "compact",
compactDisplay: "short",
maximumFractionDigits: 2,
}).format(value);
}

export function moneyFormatter(value: null | number) {
Expand Down
25 changes: 25 additions & 0 deletions src/__tests__/__snapshots__/documenter.test.ts.snap
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Expand Up @@ -232,6 +232,12 @@ This property corresponds to [chart.inverted](https://api.highcharts.com/highcha
"optional": true,
"type": "BaseLegendOptions",
},
{
"description": "The locale to be used for formatting numbers, dates, etc. Defaults to the browser locale.",
"name": "locale",
"optional": true,
"type": "string",
},
{
"description": "Defines options to represent empty, no-match, loading, and error state of the chart, including:
* \`statusType\` (optional, "finished" | "loading" | "error") - Specifies the current status of loading data.
Expand Down Expand Up @@ -879,6 +885,12 @@ Supported Highcharts versions: 12.",
"optional": true,
"type": "BaseLegendOptions",
},
{
"description": "The locale to be used for formatting numbers, dates, etc. Defaults to the browser locale.",
"name": "locale",
"optional": true,
"type": "string",
},
{
"description": "Defines options to represent empty, no-match, loading, and error state of the chart, including:
* \`statusType\` (optional, "finished" | "loading" | "error") - Specifies the current status of loading data.
Expand Down Expand Up @@ -1647,6 +1659,19 @@ Supported Highcharts versions: 12.",
"type": "CoreChartProps.LegendOptions",
"visualRefreshTag": undefined,
},
{
"analyticsTag": undefined,
"defaultValue": undefined,
"deprecatedTag": undefined,
"description": "The locale to be used for formatting numbers, dates, etc. Defaults to the browser locale.",
"i18nTag": undefined,
"inlineType": undefined,
"name": "locale",
"optional": true,
"systemTags": undefined,
"type": "string",
"visualRefreshTag": undefined,
},
{
"analyticsTag": undefined,
"defaultValue": undefined,
Expand Down
4 changes: 2 additions & 2 deletions src/core/__tests__/chart-core-axes.test.tsx
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Expand Up @@ -130,7 +130,7 @@ describe("CoreChart: axes", () => {
expect(formatter.call(mockAxisContext({ value: 1 }))).toBe("1");
expect(formatter.call(mockAxisContext({ value: 1_000 }))).toBe("1K");
expect(formatter.call(mockAxisContext({ value: 1_000_000 }))).toBe("1M");
expect(formatter.call(mockAxisContext({ value: 1_000_000_000 }))).toBe("1G");
expect(formatter.call(mockAxisContext({ value: 1_000_000_000 }))).toBe("1B");
});
});

Expand All @@ -140,7 +140,7 @@ describe("CoreChart: axes", () => {
expect(formatter.call(mockAxisContext({ value: 2.0 }))).toBe("2");
expect(formatter.call(mockAxisContext({ value: 2.03 }))).toBe("2.03");
expect(formatter.call(mockAxisContext({ value: 0.03 }))).toBe("0.03");
expect(formatter.call(mockAxisContext({ value: 0.003 }))).toBe("3e-3");
expect(formatter.call(mockAxisContext({ value: 0.003 }))).toBe("3E-3");
});
});

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2 changes: 2 additions & 0 deletions src/core/chart-api/chart-extra-context.tsx
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Expand Up @@ -32,6 +32,7 @@ export namespace ChartExtraContext {
tooltipEnabled: boolean;
keyboardNavigationEnabled: boolean;
labels: ChartLabels;
locale: string;
}

export interface Handlers {
Expand Down Expand Up @@ -63,6 +64,7 @@ export function createChartContext(): ChartExtraContext {
tooltipEnabled: false,
keyboardNavigationEnabled: false,
labels: {},
locale: "en-US",
},
handlers: {},
state: {},
Expand Down
20 changes: 16 additions & 4 deletions src/core/chart-api/index.tsx
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Expand Up @@ -265,27 +265,39 @@ export class ChartAPI {
},
onFocusGroup: (group: Highcharts.Point[]) => {
this.highlightActions(group, { isApiCall: false, overrideTooltipLock: true });
this.chartExtraNavigation.announceElement(getGroupAccessibleDescription(group), false);
this.chartExtraNavigation.announceElement(
getGroupAccessibleDescription(group, this.context.settings.locale),
false,
);
},
onFocusPoint: (point: Highcharts.Point) => {
const labels = this.context.settings.labels;
this.highlightActions(point, { isApiCall: false, overrideTooltipLock: true });
this.chartExtraNavigation.announceElement(getPointAccessibleDescription(point, labels), false);
this.chartExtraNavigation.announceElement(
getPointAccessibleDescription(point, labels, this.context.settings.locale),
false,
);
},
onBlur: () => this.clearChartHighlight({ isApiCall: false }),
onActivateGroup: () => {
const current = this.chartExtraTooltip.get();
if (current.group.length > 0) {
this.chartExtraTooltip.pinTooltip();
this.chartExtraNavigation.announceElement(getGroupAccessibleDescription(current.group), true);
this.chartExtraNavigation.announceElement(
getGroupAccessibleDescription(current.group, this.context.settings.locale),
true,
);
}
},
onActivatePoint: () => {
const current = this.chartExtraTooltip.get();
if (current.point) {
const labels = this.context.settings.labels;
this.chartExtraTooltip.pinTooltip();
this.chartExtraNavigation.announceElement(getPointAccessibleDescription(current.point, labels), true);
this.chartExtraNavigation.announceElement(
getPointAccessibleDescription(current.point, labels, this.context.settings.locale),
true,
);
}
},
};
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25 changes: 17 additions & 8 deletions src/core/chart-core.tsx
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Expand Up @@ -6,15 +6,16 @@ import clsx from "clsx";
import type Highcharts from "highcharts";
import HighchartsReact from "highcharts-react-official";

import { getIsRtl, useMergeRefs, useUniqueId } from "@cloudscape-design/component-toolkit/internal";
import { isDevelopment } from "@cloudscape-design/component-toolkit/internal";
import { getIsRtl, isDevelopment, useMergeRefs, useUniqueId } from "@cloudscape-design/component-toolkit/internal";
import { normalizeLocale } from "@cloudscape-design/component-toolkit/internal/locale";
import Spinner from "@cloudscape-design/components/spinner";

import { getDataAttributes } from "../internal/base-component/get-data-attributes";
import { InternalBaseComponentProps } from "../internal/base-component/use-base-component";
import * as Styles from "../internal/chart-styles";
import { castArray } from "../internal/utils/utils";
import { useChartAPI } from "./chart-api";
import { ChartExtraContext } from "./chart-api/chart-extra-context";
import { ChartContainer } from "./chart-container";
import { ChartApplication } from "./components/core-application";
import { ChartFilters } from "./components/core-filters";
Expand Down Expand Up @@ -66,6 +67,9 @@ export function InternalCoreChart({
...rest
}: CoreChartProps & InternalBaseComponentProps) {
const highcharts = rest.highcharts as null | typeof Highcharts;

const locale = normalizeLocale("InternalCoreChart", rest.locale ?? null);

const labels = useChartI18n({ ariaLabel, ariaDescription, i18nStrings });
const context = {
chartId: useUniqueId(),
Expand All @@ -74,7 +78,8 @@ export function InternalCoreChart({
tooltipEnabled: tooltipOptions?.enabled !== false,
keyboardNavigationEnabled: keyboardNavigation,
labels,
};
locale,
} satisfies ChartExtraContext.Settings;
const handlers = { onHighlight, onClearHighlight, onVisibleItemsChange };
const state = { visibleItems };
const api = useChartAPI(context, handlers, state);
Expand Down Expand Up @@ -179,7 +184,7 @@ export function InternalCoreChart({
keyboardNavigation: options.accessibility?.keyboardNavigation ?? { enabled: !keyboardNavigation },
point: {
// Point description formatter is overridden to respect custom axes value formatters.
descriptionFormatter: (point) => getPointAccessibleDescription(point, labels),
descriptionFormatter: (point) => getPointAccessibleDescription(point, labels, locale),
...options.accessibility?.point,
},
},
Expand All @@ -193,7 +198,7 @@ export function InternalCoreChart({
opposite: inverted && isRtl ? !xAxisOptions.opposite : xAxisOptions.opposite,
className: xAxisClassName(inverted, xAxisOptions.className),
title: axisTitle(xAxisOptions.title ?? {}, !inverted || verticalAxisTitlePlacement === "side"),
labels: axisLabels(xAxisOptions.labels ?? {}),
labels: axisLabels(xAxisOptions.labels ?? {}, locale),
})),
yAxis: castArray(options.yAxis)?.map((yAxisOptions) => ({
...Styles.yAxisOptions,
Expand All @@ -203,7 +208,7 @@ export function InternalCoreChart({
opposite: !inverted && isRtl ? !yAxisOptions.opposite : yAxisOptions.opposite,
className: yAxisClassName(inverted, yAxisOptions.className),
title: axisTitle(yAxisOptions.title ?? {}, inverted || verticalAxisTitlePlacement === "side"),
labels: axisLabels(yAxisOptions.labels ?? {}),
labels: axisLabels(yAxisOptions.labels ?? {}, locale),
plotLines: yAxisPlotLines(yAxisOptions.plotLines, emphasizeBaseline),
// We use reversed stack by default so that the order of points in the tooltip and series in the legend
// correspond the order of stacks.
Expand Down Expand Up @@ -356,6 +361,7 @@ export function InternalCoreChart({

{context.tooltipEnabled && (
<ChartTooltip
locale={locale}
{...tooltipOptions}
i18nStrings={i18nStrings}
getTooltipContent={rest.getTooltipContent}
Expand Down Expand Up @@ -399,11 +405,14 @@ function axisTitle<O extends Highcharts.XAxisTitleOptions | Highcharts.YAxisTitl

// We use custom formatters instead of Highcharts defaults to ensure consistent formatting
// between axis ticks and tooltip contents.
function axisLabels<O extends Highcharts.XAxisLabelsOptions | Highcharts.YAxisLabelsOptions>(options: O): O {
function axisLabels<O extends Highcharts.XAxisLabelsOptions | Highcharts.YAxisLabelsOptions>(
options: O,
locale: string,
): O {
return {
style: Styles.axisLabelsCss,
formatter: function () {
const formattedValue = getFormatter(this.axis)(this.value);
const formattedValue = getFormatter(locale, this.axis)(this.value);
return formattedValue.replace(/\n/g, "<br />");
},
...options,
Expand Down
10 changes: 8 additions & 2 deletions src/core/components/core-tooltip.tsx
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Expand Up @@ -46,12 +46,14 @@ export function ChartTooltip({
getTooltipContent: getTooltipContentOverrides,
api,
i18nStrings,
locale,
debounce = false,
seriesSorting = "as-added",
}: CoreChartProps.TooltipOptions & {
i18nStrings?: BaseI18nStrings;
getTooltipContent?: CoreChartProps.GetTooltipContent;
api: ChartAPI;
locale: string;
}) {
const [expandedSeries, setExpandedSeries] = useState<ExpandedSeriesState>({});
const tooltip = useSelector(api.tooltipStore, (s) => s);
Expand Down Expand Up @@ -86,6 +88,7 @@ export function ChartTooltip({
hideTooltip: () => {
api.hideTooltip();
},
locale,
});
if (!content) {
return null;
Expand Down Expand Up @@ -135,6 +138,7 @@ function getTooltipContent(
renderers?: CoreChartProps.TooltipContentRenderer;
hideTooltip: () => void;
seriesSorting: NonNullable<CoreChartProps.TooltipOptions["seriesSorting"]>;
locale: string;
} & ExpandedSeriesStateProps,
): null | RenderedTooltipContent {
if (props.point && props.point.series.type === "pie") {
Expand All @@ -156,8 +160,10 @@ function getTooltipContentCartesian(
setExpandedSeries,
hideTooltip,
seriesSorting,
locale,
}: CoreChartProps.GetTooltipContentProps & {
renderers?: CoreChartProps.TooltipContentRenderer;
locale: string;
hideTooltip: () => void;
seriesSorting: NonNullable<CoreChartProps.TooltipOptions["seriesSorting"]>;
} & ExpandedSeriesStateProps,
Expand All @@ -170,7 +176,7 @@ function getTooltipContentCartesian(
api.renderMarker(getSeriesMarkerType(series), getSeriesColor(series), true);
const matchedItems = findTooltipSeriesItems(getChartSeries(chart.series), group, seriesSorting);
const detailItems: ChartSeriesDetailItem[] = matchedItems.map((item) => {
const valueFormatter = getFormatter(item.point.series.yAxis);
const valueFormatter = getFormatter(locale, item.point.series.yAxis);
const itemY = isXThreshold(item.point.series) ? null : (item.point.y ?? null);
const customContent = renderers.point
? renderers.point({
Expand Down Expand Up @@ -203,7 +209,7 @@ function getTooltipContentCartesian(
};
});
// We only support cartesian charts with a single x axis.
const titleFormatter = getFormatter(chart.xAxis[0]);
const titleFormatter = getFormatter(locale, chart.xAxis[0]);
const slotRenderProps: CoreChartProps.TooltipSlotProps = {
x,
items: matchedItems,
Expand Down
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