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fix(i18n): honor the requested currency in formatCurrency #975

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thlpkee20-wq merged 2 commits into from
Oct 22, 2026
Merged

fix(i18n): honor the requested currency in formatCurrency #975

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5ffdcfe
fix(i18n): honor the requested currency in formatCurrency (#920)
temisan0x Oct 19, 2026
e137622
test(i18n): compare GBP in ja-JP against Intl instead of a hard-coded…
temisan0x Oct 19, 2026
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22 changes: 22 additions & 0 deletions src/constants/i18n.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,28 @@ describe("i18n utility functions", () => {
expect(formatCurrency(1200, "USD", "en-US")).toContain("$");
});

it("uses the requested currency even when the locale has a different default", () => {
const usdInGerman = formatCurrency(100, "USD", "de-DE");
expect(usdInGerman).toContain("$");
expect(usdInGerman).not.toContain("€");
expect(formatCurrency(100, "EUR", "en-US")).toContain("€");
expect(formatCurrency(100, "GBP", "ja-JP")).toBe(
new Intl.NumberFormat("ja-JP", { style: "currency", currency: "GBP" }).format(100),
);
});

it("falls back to the locale default currency when none is requested", () => {
expect(formatCurrency(100, undefined, "de-DE")).toContain("€");
expect(formatCurrency(100, undefined, "ja-JP")).toBe(
new Intl.NumberFormat("ja-JP", { style: "currency", currency: "JPY" }).format(100),
);
});

it("only drops decimals when the requested currency is JPY", () => {
expect(formatCurrency(1234.5, "JPY", "en-US")).not.toMatch(/\.\d/);
expect(formatCurrency(1234.5, "USD", "ja-JP")).toContain(".50");
});

it("formats dates using locale settings", () => {
expect(formatDate("2026-05-10", "en-US")).toContain("2026");
expect(formatDate("2026-05-10", "de-DE")).toContain("2026");
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20 changes: 10 additions & 10 deletions src/constants/i18n.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "USD",
date: { year: "numeric", month: "short", day: "numeric" },
number: { maximumFractionDigits: 2 },
currency: { style: "currency", currency: "USD", currencyDisplay: "symbol", maximumFractionDigits: 2 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
"de-DE": {
code: "de-DE",
Expand All @@ -71,7 +71,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "EUR",
date: { year: "numeric", month: "numeric", day: "numeric" },
number: { maximumFractionDigits: 2 },
currency: { style: "currency", currency: "EUR", currencyDisplay: "symbol", maximumFractionDigits: 2 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
"ja-JP": {
code: "ja-JP",
Expand All @@ -80,7 +80,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "JPY",
date: { year: "numeric", month: "numeric", day: "numeric" },
number: { maximumFractionDigits: 0, useGrouping: true },
currency: { style: "currency", currency: "JPY", currencyDisplay: "symbol", maximumFractionDigits: 0 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
"ar-SA": {
code: "ar-SA",
Expand All @@ -89,7 +89,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "SAR",
date: { year: "numeric", month: "numeric", day: "numeric" },
number: { maximumFractionDigits: 2, useGrouping: true },
currency: { style: "currency", currency: "SAR", currencyDisplay: "symbol", maximumFractionDigits: 2 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
"fr-FR": {
code: "fr-FR",
Expand All @@ -98,7 +98,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "EUR",
date: { year: "numeric", month: "numeric", day: "numeric" },
number: { maximumFractionDigits: 2 },
currency: { style: "currency", currency: "EUR", currencyDisplay: "symbol", maximumFractionDigits: 2 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
"es-ES": {
code: "es-ES",
Expand All @@ -107,7 +107,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "EUR",
date: { year: "numeric", month: "numeric", day: "numeric" },
number: { maximumFractionDigits: 2 },
currency: { style: "currency", currency: "EUR", currencyDisplay: "symbol", maximumFractionDigits: 2 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
"zh-CN": {
code: "zh-CN",
Expand All @@ -116,7 +116,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "CNY",
date: { year: "numeric", month: "numeric", day: "numeric" },
number: { maximumFractionDigits: 2, useGrouping: true },
currency: { style: "currency", currency: "CNY", currencyDisplay: "symbol", maximumFractionDigits: 2 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
"en-GB": {
code: "en-GB",
Expand All @@ -125,7 +125,7 @@ export const LOCALE_FORMAT_SETTINGS: Record<string, LocaleMeta> = {
defaultCurrency: "GBP",
date: { year: "numeric", month: "short", day: "numeric" },
number: { maximumFractionDigits: 2 },
currency: { style: "currency", currency: "GBP", currencyDisplay: "symbol", maximumFractionDigits: 2 },
currency: { style: "currency", currencyDisplay: "symbol" },
},
};

Expand Down Expand Up @@ -165,13 +165,13 @@ export function formatCurrency(
locale: string = "en-US",
options: Intl.NumberFormatOptions = {},
): string {
const defaultCurr = currency ?? LOCALE_FORMAT_SETTINGS[locale]?.defaultCurrency ?? "USD";
const resolvedCurrency = currency ?? LOCALE_FORMAT_SETTINGS[locale]?.defaultCurrency ?? "USD";
const setting = LOCALE_FORMAT_SETTINGS[locale]?.currency ?? {};
return new Intl.NumberFormat(locale, {
style: "currency",
currency: defaultCurr,
currencyDisplay: "symbol",
...setting,
currency: resolvedCurrency,
...options,
}).format(value);
}
Expand Down