Add a `Number.isNaN` polyfill

Reviewed By: sahrens

Differential Revision: D3222299

fb-gh-sync-id: 601283fb0b140bb305181ea381907e62286f7a37
fbshipit-source-id: 601283fb0b140bb305181ea381907e62286f7a37

react-packager/src/Resolver/__tests__/Resolver-test.js

@@ -143,12 +143,21 @@ describe('Resolver', function() {
                 'polyfills/console.js'
               ],
             },
+            { id: 'polyfills/Number.es6.js',
+              file: 'polyfills/Number.es6.js',
+              dependencies: [
+                'polyfills/polyfills.js',
+                'polyfills/console.js',
+                'polyfills/error-guard.js'
+              ],
+            },
             { id: 'polyfills/String.prototype.es6.js',
               file: 'polyfills/String.prototype.es6.js',
               dependencies: [
                 'polyfills/polyfills.js',
                 'polyfills/console.js',
-                'polyfills/error-guard.js'
+                'polyfills/error-guard.js',
+                'polyfills/Number.es6.js',
               ],
             },
             { id: 'polyfills/Array.prototype.es6.js',
@@ -157,6 +166,7 @@ describe('Resolver', function() {
                 'polyfills/polyfills.js',
                 'polyfills/console.js',
                 'polyfills/error-guard.js',
+                'polyfills/Number.es6.js',
                 'polyfills/String.prototype.es6.js',
               ],
             },
@@ -166,6 +176,7 @@ describe('Resolver', function() {
                 'polyfills/polyfills.js',
                 'polyfills/console.js',
                 'polyfills/error-guard.js',
+                'polyfills/Number.es6.js',
                 'polyfills/String.prototype.es6.js',
                 'polyfills/Array.prototype.es6.js',
               ],
@@ -176,6 +187,7 @@ describe('Resolver', function() {
                 'polyfills/polyfills.js',
                 'polyfills/console.js',
                 'polyfills/error-guard.js',
+                'polyfills/Number.es6.js',
                 'polyfills/String.prototype.es6.js',
                 'polyfills/Array.prototype.es6.js',
                 'polyfills/Array.es6.js',
@@ -187,6 +199,7 @@ describe('Resolver', function() {
                 'polyfills/polyfills.js',
                 'polyfills/console.js',
                 'polyfills/error-guard.js',
+                'polyfills/Number.es6.js',
                 'polyfills/String.prototype.es6.js',
                 'polyfills/Array.prototype.es6.js',
                 'polyfills/Array.es6.js',
@@ -251,6 +264,7 @@ describe('Resolver', function() {
                 'polyfills/polyfills.js',
                 'polyfills/console.js',
                 'polyfills/error-guard.js',
+                'polyfills/Number.es6.js',
                 'polyfills/String.prototype.es6.js',
                 'polyfills/Array.prototype.es6.js',
                 'polyfills/Array.es6.js',

react-packager/src/Resolver/index.js

@@ -177,6 +177,7 @@ class Resolver {
       path.join(__dirname, 'polyfills/polyfills.js'),
       path.join(__dirname, 'polyfills/console.js'),
       path.join(__dirname, 'polyfills/error-guard.js'),
+      path.join(__dirname, 'polyfills/Number.es6.js'),
       path.join(__dirname, 'polyfills/String.prototype.es6.js'),
       path.join(__dirname, 'polyfills/Array.prototype.es6.js'),
       path.join(__dirname, 'polyfills/Array.es6.js'),

react-packager/src/Resolver/polyfills/Number.es6.js

@@ -0,0 +1,24 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @provides Number.es6
+ * @polyfill
+ */
+
+if (!Number.isNaN) {
+  // https://github.com/dherman/tc39-codex-wiki/blob/master/data/es6/number/index.md#polyfill-for-numberisnan
+  const globalIsNaN = global.isNaN;
+  Object.defineProperty(Number, 'isNaN', {
+    configurable: true,
+    enumerable: false,
+    value: function isNaN(value) {
+      return typeof value === 'number' && globalIsNaN(value);
+    },
+    writable: true,
+  });
+}

react-packager/src/Resolver/polyfills/__tests__/Number.es6.js

@@ -0,0 +1,45 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @emails oncall+jsinfra
+ */
+
+jest.autoMockOff();
+
+describe('Number (ES6)', () => {
+  describe('isNaN()', () => {
+    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN#Examples
+    beforeEach(() => {
+      delete Number.isNaN;
+      jest.resetModuleRegistry();
+      require('../Number.es6');
+    });
+    it('returns true when fed something that is not-a-number', () => {
+      [
+        NaN,
+        Number.NaN,
+        0 / 0,
+      ].forEach(value => expect(Number.isNaN(value)).toBe(true));
+    });
+    it('returns false when fed something other than not-a-number', () => {
+      [
+        'NaN',
+        undefined,
+        {},
+        'blabla',
+        true,
+        null,
+        37,
+        '37',
+        '37.37',
+        '',
+        ' ',
+      ].forEach(value => expect(Number.isNaN(value)).toBe(false));
+    });
+  });
+});