Add localizeCurrency and specs

app/webpacker/js/services/localize_currency.js

@@ -0,0 +1,24 @@
+// Convert number to string currency using injected currency configuration.
+
+// Requires global variable from page: ofn_currency_config
+export default function (amount) {
+  // Set country code (eg. "US").
+  const currency_code = ofn_currency_config.display_currency
+    ? " " + ofn_currency_config.currency
+    : "";
+  // Set decimal points, 2 or 0 if hide_cents.
+  const decimals = ofn_currency_config.hide_cents === "true" ? 0 : 2;
+  // Set format if the currency symbol should come after the number, otherwise (default) use the locale setting.
+  const format = ofn_currency_config.symbol_position === "after" ? "%n %u" : undefined;
+  // We need to use parseFloat as the amount should come in as a string.
+  amount = parseFloat(amount);
+
+  // Build the final price string.
+  return (
+    I18n.toCurrency(amount, {
+      precision: decimals,
+      unit: ofn_currency_config.symbol,
+      format: format,
+    }) + currency_code
+  );
+}

spec/javascripts/services/localize_currency_test.js

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+/**
+ * @jest-environment jsdom
+ */
+
+import localizeCurrency from "js/services/localize_currency";
+
+describe("convert number to localised currency", function () {
+  beforeAll(() => {
+    const mockedToCurrency = jest.fn();
+    mockedToCurrency.mockImplementation((amount, options) => {
+      if (options.format == "%n %u") {
+        return `${amount.toFixed(options.precision)}${options.unit}`;
+      } else {
+        return `${options.unit}${amount.toFixed(options.precision)}`;
+      }
+    });
+
+    global.I18n = { toCurrency: mockedToCurrency };
+
+    // Requires global var from page
+    global.ofn_currency_config = {
+      symbol: "$",
+      symbol_position: "before",
+      currency: "D",
+      hide_cents: "false",
+    };
+  });
+  // (jest still doesn't have aroundEach https://github.com/jestjs/jest/issues/4543 )
+  afterAll(() => {
+    delete global.I18n;
+  });
+
+  it("adds decimal fraction to an amount", function () {
+    expect(localizeCurrency(10)).toEqual("$10.00");
+  });
+
+  it("handles an existing fraction", function () {
+    expect(localizeCurrency(9.9)).toEqual("$9.90");
+  });
+
+  it("can use any currency symbol", function () {
+    global.ofn_currency_config.symbol = "£";
+    expect(localizeCurrency(404.04)).toEqual("£404.04");
+  });
+
+  it("can place symbols after the amount", function () {
+    global.ofn_currency_config.symbol = "$";
+    global.ofn_currency_config.symbol_position = "after";
+    expect(localizeCurrency(333.3)).toEqual("333.30$");
+  });
+
+  it("can add a currency string", function () {
+    global.ofn_currency_config.display_currency = true;
+    global.ofn_currency_config.symbol_position = "before";
+    expect(localizeCurrency(5)).toEqual("$5.00 D");
+  });
+
+  it("can hide cents", function () {
+    global.ofn_currency_config.display_currency = false;
+    global.ofn_currency_config.hide_cents = "true";
+    expect(localizeCurrency(5)).toEqual("$5");
+  });
+});