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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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31 changes: 13 additions & 18 deletions pages/common/formatters.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -17,36 +17,31 @@ export function dateFormatter(value: null | number) {
.join("\n");
}

export function numberFormatter(value: null | number) {
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 •
edited
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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: 9,
}).format(value);
}

return format(value);
// Use compact notation for normal range
return new Intl.NumberFormat(locale, {
notation: "compact",
compactDisplay: "short",
maximumFractionDigits: 9,
}).format(value);
}

export function moneyFormatter(value: null | number) {
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6 changes: 4 additions & 2 deletions src/core/__tests__/chart-core-axes.test.tsx
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Expand Up @@ -126,11 +126,12 @@ describe("CoreChart: axes", () => {
test("uses default numeric axes formatters for integer values", () => {
renderChart({ highcharts, options: { series, xAxis: { title: { text: "X" } }, yAxis: { title: { text: "Y" } } } });
getAxisOptionsFormatters().forEach((formatter) => {
// See https://www.unicode.org/cldr/cldr-aux/charts/29/verify/numbers/en.html
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@pan-kot pan-kot Nov 12, 2025

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let's better add this reference to the formatter function, not tests

expect(formatter.call(mockAxisContext({ value: 0 }))).toBe("0");
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 +141,8 @@ 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("0.003");
expect(formatter.call(mockAxisContext({ value: 0.0000000003 }))).toBe("3E-10");
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@jperals jperals Nov 4, 2025

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Why is the "E" uppercase?

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@Pixselve Pixselve Nov 4, 2025 •
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It is based on the Unicode Common Locale Data Repository. See https://cldr.unicode.org/translation/number-currency-formats/number-and-currency-patterns

Type Example pattern Meaning
E # E 0 This marks a scientific format. The E symbol may change position. Must be retained.

});
});

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31 changes: 13 additions & 18 deletions src/core/formatters.tsx
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Expand Up @@ -102,30 +102,25 @@ function secondFormatter(value: number) {
});
}

function numberFormatter(value: number): string {
const format = (num: number) => parseFloat(num.toFixed(2)).toString(); // trims unnecessary decimals

function numberFormatter(value: number, locale: string = "en-US"): string {
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@pan-kot pan-kot Nov 12, 2025

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should we take locale from the document instead?

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@Pixselve Pixselve Nov 24, 2025

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Made a PR to share the locale getting logic: cloudscape-design/component-toolkit#176

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) {
return new Intl.NumberFormat(locale, {
notation: "scientific",
maximumFractionDigits: 9,
}).format(value);
}

return format(value);
// Use compact notation for normal range
return new Intl.NumberFormat(locale, {
notation: "compact",
compactDisplay: "short",
maximumFractionDigits: 9,
}).format(value);
}
2 changes: 1 addition & 1 deletion tsconfig.json
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Expand Up @@ -5,7 +5,7 @@
"target": "ES2019",
"jsx": "react-jsx",
"types": [],
"lib": ["es2019", "dom", "dom.iterable"],
"lib": ["es2020", "dom", "dom.iterable"],
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@pan-kot pan-kot Nov 12, 2025

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Why is this change needed?

"module": "ESNext",
"moduleResolution": "Node",
"esModuleInterop": true,
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