JS: Use Object.defineProperty for Array Polyfills

react-packager/src/DependencyResolver/haste/polyfills/Array.prototype.es6.js

@@ -3,53 +3,14 @@
  *
  * @provides Array.prototype.es6
  * @polyfill
- * @requires __DEV__
  */
 
 /*eslint-disable */
 /*jslint bitwise: true */
 
-(function (undefined) {
-  if (__DEV__) {
-    // Define DEV-only setter that blows up when someone incorrectly
-    // iterates over arrays.
-    try {
-      Object.defineProperty && Object.defineProperty(
-        Array.prototype,
-        '__ARRAY_ENUMERATION_GUARD__',
-        {
-          configurable: true,
-          enumerable: true,
-          get: function() {
-            console.error(
-              'Your code is broken! Do not iterate over arrays with ' +
-              'for...in.'
-            );
-          }
-        }
-      );
-    } catch (e) {
-      // Nothing
-    }
-  }
-
+(function(undefined) {
   // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex
   function findIndex(predicate, context) {
-    /**
-     * Why am I seeing this "findIndex" method as a value in my array!?
-     *
-     * We polyfill the "findIndex" method -- called like
-     * `[1, 2, 3].findIndex(1)` -- for older browsers. A side effect of the way
-     * we do that is that the method is enumerable. If you were incorrectly
-     * iterating over your array using the object property iterator syntax
-     * `for (key in obj)` you will see the method name "findIndex" as a key.
-     *
-     * To fix your code please do one of the following:
-     *
-     *  - Use a regular for loop with index.
-     *  - Use one of the array methods: a.forEach, a.map, etc.
-     *  - Guard your body of your loop with a `arr.hasOwnProperty(key)` check.
-     */
     if (this == null) {
       throw new TypeError(
         'Array.prototype.findIndex called on null or undefined'
@@ -69,32 +30,29 @@
   }
 
   if (!Array.prototype.findIndex) {
-    Array.prototype.findIndex = findIndex;
+    Object.defineProperty(Array.prototype, 'findIndex', {
+      enumerable: false,
+      writable: true,
+      configurable: true,
+      value: findIndex
+    });
   }
 
   // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find
   if (!Array.prototype.find) {
-    Array.prototype.find = function(predicate, context) {
-      /**
-       * Why am I seeing this "find" method as a value in my array!?
-       *
-       * We polyfill the "find" method -- called like
-       * `[1, 2, 3].find(1)` -- for older browsers. A side effect of the way
-       * we do that is that the method is enumerable. If you were incorrectly
-       * iterating over your array using the object property iterator syntax
-       * `for (key in obj)` you will see the method name "find" as a key.
-       *
-       * To fix your code please do one of the following:
-       *
-       *  - Use a regular for loop with index.
-       *  - Use one of the array methods: a.forEach, a.map, etc.
-       *  - Guard your body of your loop with a `arr.hasOwnProperty(key)` check.
-       */
-      if (this == null) {
-        throw new TypeError('Array.prototype.find called on null or undefined');
+    Object.defineProperty(Array.prototype, 'find', {
+      enumerable: false,
+      writable: true,
+      configurable: true,
+      value: function(predicate, context) {
+        if (this == null) {
+          throw new TypeError(
+            'Array.prototype.find called on null or undefined'
+          );
+        }
+        var index = findIndex.call(this, predicate, context);
+        return index === -1 ? undefined : this[index];
       }
-      var index = findIndex.call(this, predicate, context);
-      return index === -1 ? undefined : this[index];
-    };
+    });
   }
 })();