Add d3.formatDefaultLocale.

README.md

@@ -63,7 +63,7 @@ d3.format("#x")(48879);   // prefixed lowercase hexadecimal, "0xbeef"
 d3.format(",.2r")(4223);  // grouped thousands with two significant digits, "4,200"
 ```
 
-See [*locale*.format](#locale_format) for a detailed specification, and try running [formatSpecifier](#formatSpecifier) on the above formats to decode their meaning.
+See [*locale*.format](#locale_format) for a detailed specification, and try running [d3.formatSpecifier](#formatSpecifier) on the above formats to decode their meaning.
 
 ## Installing
 
@@ -84,11 +84,11 @@ var format = d3.format(".2s");
 
 <a name="format" href="#format">#</a> d3.<b>format</b>(<i>specifier</i>)
 
-An alias for [*locale*.format](#locale_format) on the U.S. English locale. See [formatLocale](#formatLocale) to define a new locale.
+An alias for [*locale*.format](#locale_format) on the default locale. See [d3.formatDefaultLocale](#formatDefaultLocale) to set the default locale, and [d3.formatLocale](#formatLocale) to define a new locale.
 
 <a name="formatPrefix" href="#formatPrefix">#</a> d3.<b>formatPrefix</b>(<i>specifier</i>, <i>value</i>)
 
-An alias for [*locale*.formatPrefix](#locale_formatPrefix) on the U.S. English locale. See [formatLocale](#formatLocale) to define a new locale.
+An alias for [*locale*.formatPrefix](#locale_formatPrefix) on the default locale. See [d3.formatDefaultLocale](#formatDefaultLocale) to set the default locale, and [d3.formatLocale](#formatLocale) to define a new locale.
 
 <a name="locale_format" href="#locale_format">#</a> <i>locale</i>.<b>format</b>(<i>specifier</i>)
 
@@ -293,3 +293,7 @@ Returns a *locale* object for the specified *definition* with [*locale*.format](
 * `currency` - the currency prefix and suffix (e.g., `["$", ""]`).
 
 Note that the *thousands* property is a misnomer, as the grouping definition allows groups other than thousands.
+
+<a name="formatDefaultLocale" href="#formatDefaultLocale">#</a> d3.<b>formatDefaultLocale</b>(<i>definition</i>)
+
+Equivalent to [d3.formatLocale](#formatLocale), except it also redefines [d3.format](#format) and [d3.formatPrefix](#formatPrefix) to the new locale’s [*locale*.format](#locale_format) and [*locale*.formatPrefix](#locale_formatPrefix). If you do not set a default locale, it defaults to [U.S. English](https://github.com/d3/d3-format/blob/master/locale/en-US.json).

index.js

@@ -1,4 +1,5 @@
-export {default as formatLocale, format, formatPrefix} from "./src/locale";
+export {default as formatDefaultLocale, format, formatPrefix} from "./src/defaultLocale";
+export {default as formatLocale} from "./src/locale";
 export {default as formatSpecifier} from "./src/formatSpecifier";
 export {default as precisionFixed} from "./src/precisionFixed";
 export {default as precisionPrefix} from "./src/precisionPrefix";

src/defaultLocale.js

@@ -0,0 +1,19 @@
+import formatLocale from "./locale";
+
+var locale;
+export var format;
+export var formatPrefix;
+
+defaultLocale({
+  decimal: ".",
+  thousands: ",",
+  grouping: [3],
+  currency: ["$", ""]
+});
+
+export default function defaultLocale(definition) {
+  locale = formatLocale(definition);
+  format = locale.format;
+  formatPrefix = locale.formatPrefix;
+  return locale;
+}

src/locale.js

@@ -10,17 +10,7 @@ function identity(x) {
   return x;
 }
 
-var defaultLocale = formatLocale({
-  decimal: ".",
-  thousands: ",",
-  grouping: [3],
-  currency: ["$", ""]
-});
-
-export var format = defaultLocale.format;
-export var formatPrefix = defaultLocale.formatPrefix;
-
-export default function formatLocale(locale) {
+export default function(locale) {
   var group = locale.grouping && locale.thousands ? formatGroup(locale.grouping, locale.thousands) : identity,
       currency = locale.currency,
       decimal = locale.decimal;

test/defaultLocale-test.js

@@ -0,0 +1,48 @@
+var tape = require("tape"),
+    d3 = require("../");
+
+var enUs = {
+  "decimal": ".",
+  "thousands": ",",
+  "grouping": [3],
+  "currency": ["$", ""]
+};
+
+var frFr = {
+  "decimal": ",",
+  "thousands": ".",
+  "grouping": [3],
+  "currency": ["", "\u00a0€"]
+};
+
+tape("d3.formatDefaultLocale(definition) returns the new default locale", function(test) {
+  var locale = d3.formatDefaultLocale(frFr);
+  try {
+    test.equal(locale.format("$,.2f")(12345678.90), "12.345.678,90 €");
+    test.end();
+  } finally {
+    d3.formatDefaultLocale(enUs);
+  }
+});
+
+tape("d3.formatDefaultLocale(definition) affects d3.format", function(test) {
+  var locale = d3.formatDefaultLocale(frFr);
+  try {
+    test.equal(d3.format, locale.format);
+    test.equal(d3.format("$,.2f")(12345678.90), "12.345.678,90 €");
+    test.end();
+  } finally {
+    d3.formatDefaultLocale(enUs);
+  }
+});
+
+tape("d3.formatDefaultLocale(definition) affects d3.formatPrefix", function(test) {
+  var locale = d3.formatDefaultLocale(frFr);
+  try {
+    test.equal(d3.formatPrefix, locale.formatPrefix);
+    test.equal(d3.formatPrefix(",.2", 1e3)(12345678.90), "12.345,68k");
+    test.end();
+  } finally {
+    d3.formatDefaultLocale(enUs);
+  }
+});