Use Intl.NumberFormat to format numbers

README.md

@@ -243,6 +243,25 @@ polyglot.t("car", 2);
 => "2 cars"
 ```
 
+Interpolated `Number`s will be number-formatted according to the `locale`:
+
+```js
+polyglot.t("num_cars", 2000);
+=> "2,000 cars"
+```
+
+On a default Node install, this may only work in English. To format in
+non-English locales (e.g., to output "2.000" in France or use other numerals),
+compile Node with "full" ICU data or include the `full-icu` package in your
+project:
+
+1. `npm install --save full-icu`
+2. Run `node --full-data-dir=node_modules/full-icu` instead of just `node`, or
+   set the `NODE_ICU_DATA=node_modules/full-icu` environment variable.
+
+If you're running Polyglot within a browser, it can number-format in any
+locale the web browser supports.
+
 If you like, you can provide a default value in case the phrase is missing.
 Use the special option key "_" to specify a default.
 

index.js

@@ -119,7 +119,7 @@ var tokenRegex = /%\{(.*?)\}/g;
 //
 // You should pass in a third argument, the locale, to specify the correct plural type.
 // It defaults to `'en'` with 2 plural forms.
-function transformPhrase(phrase, substitutions, locale) {
+function transformPhrase(phrase, substitutions, locale, numberFormat) {
   if (typeof phrase !== 'string') {
     throw new TypeError('Polyglot.transformPhrase expects argument #1 to be string');
   }
@@ -144,8 +144,14 @@ function transformPhrase(phrase, substitutions, locale) {
   // Interpolate: Creates a `RegExp` object for each interpolation placeholder.
   result = result.replace(tokenRegex, function (expression, argument) {
     if (!has(options, argument)) { return ''; }
+
+    var replacement = options[argument];
+    if (typeof replacement === 'number') {
+      replacement = numberFormat.format(replacement);
+    }
+
     // Ensure replacement value is escaped to prevent special $-prefixed regex replace tokens.
-    return replace.call(options[argument], dollarRegex, dollarBillsYall);
+    return replace.call(replacement, dollarRegex, dollarBillsYall);
   });
 
   return result;
@@ -157,6 +163,12 @@ function Polyglot(options) {
   this.phrases = {};
   this.extend(opts.phrases || {});
   this.currentLocale = opts.locale || 'en';
+  if (typeof Intl === 'object') {
+    this.numberFormat = new Intl.NumberFormat(this.currentLocale);
+  } else {
+    // Fallback for IE<11
+    this.numberFormat = { format: function (n) { return String(n); } };
+  }
   this.allowMissing = !!opts.allowMissing;
   this.warn = opts.warn || warn;
 }
@@ -165,7 +177,15 @@ function Polyglot(options) {
 //
 // Get or set locale. Internally, Polyglot only uses locale for pluralization.
 Polyglot.prototype.locale = function (newLocale) {
-  if (newLocale) this.currentLocale = newLocale;
+  if (newLocale) {
+    this.currentLocale = newLocale;
+    if (typeof Intl === 'object') {
+      this.numberFormat = new Intl.NumberFormat(this.currentLocale);
+    } else {
+      // Fallback for IE<11
+      this.numberFormat = { format: function (n) { return String(n); } };
+    }
+  }
   return this.currentLocale;
 };
 
@@ -314,7 +334,7 @@ Polyglot.prototype.t = function (key, options) {
     result = key;
   }
   if (typeof phrase === 'string') {
-    result = transformPhrase(phrase, opts, this.currentLocale);
+    result = transformPhrase(phrase, opts, this.currentLocale, this.numberFormat);
   }
   return result;
 };

package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "pretest": "npm run --silent lint",
     "test": "npm run --silent tests-only",
-    "tests-only": "mocha test/*.js --reporter spec",
+    "tests-only": "NODE_ICU_DATA=node_modules/full-icu mocha test/*.js --reporter spec",
     "lint": "eslint *.js test/*.js",
     "docs": "docco -o docs/ index.js"
   },
@@ -36,6 +36,7 @@
     "eslint": "^3.9.1",
     "eslint-config-airbnb-base": "^10.0.1",
     "eslint-plugin-import": "^2.2.0",
+    "full-icu": "^1.0.3",
     "mocha": "^3.1.2",
     "should": "^11.1.1",
     "uglify-js": "2.7.3"

test/index.js

@@ -8,7 +8,8 @@ describe('t', function () {
     hello: 'Hello',
     hi_name_welcome_to_place: 'Hi, %{name}, welcome to %{place}!',
     name_your_name_is_name: '%{name}, your name is %{name}!',
-    empty_string: ''
+    empty_string: '',
+    number: '%{number}'
   };
 
   var polyglot;
@@ -89,6 +90,14 @@ describe('t', function () {
     expect(instance.t('nav.cta.join_now')).to.equal('Join now!');
     expect(instance.t('header.sign_in')).to.equal('Sign In');
   });
+
+  it('uses an Intl.NumberFormat', function () {
+    var en = new Polyglot({ phrases: phrases, locale: 'en' });
+    var fr = new Polyglot({ phrases: phrases, locale: 'fr' });
+
+    expect(en.t('number', { number: 1234.56 })).to.equal('1,234.56');
+    expect(fr.t('number', { number: 1234.56 })).to.equal('1 234,56');
+  });
 });
 
 describe('pluralize', function () {
@@ -165,6 +174,12 @@ describe('locale', function () {
     polyglot.locale('fr');
     expect(polyglot.locale()).to.equal('fr');
   });
+
+  it('updates number format when setting locale', function () {
+    polyglot.locale('fr');
+    polyglot.extend({ x: '%{n}' });
+    expect(polyglot.t('x', { n: 1234.56 })).to.equal('1 234,56');
+  });
 });
 
 describe('extend', function () {