diff --git a/Libraries/Utilities/differ/__tests__/deepDiffer-test.js b/Libraries/Utilities/differ/__tests__/deepDiffer-test.js
new file mode 100644
index 000000000..745b83ab0
--- /dev/null
+++ b/Libraries/Utilities/differ/__tests__/deepDiffer-test.js
@@ -0,0 +1,102 @@
+/**
+ * Copyright (c) 2015-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.
+ */
+'use strict';
+
+jest.dontMock('deepDiffer');
+var deepDiffer = require('deepDiffer');
+
+describe('deepDiffer', function() {
+  it('should diff primitives of the same type', () => {
+    expect(deepDiffer(1, 2)).toBe(true);
+    expect(deepDiffer(42, 42)).toBe(false);
+    expect(deepDiffer('foo', 'bar')).toBe(true);
+    expect(deepDiffer('foo', 'foo')).toBe(false);
+    expect(deepDiffer(true, false)).toBe(true);
+    expect(deepDiffer(false, true)).toBe(true);
+    expect(deepDiffer(true, true)).toBe(false);
+    expect(deepDiffer(false, false)).toBe(false);
+    expect(deepDiffer(null, null)).toBe(false);
+    expect(deepDiffer(undefined, undefined)).toBe(false);
+  });
+  it('should diff primitives of different types', () => {
+    expect(deepDiffer(1, '1')).toBe(true);
+    expect(deepDiffer(true, 'true')).toBe(true);
+    expect(deepDiffer(true, 1)).toBe(true);
+    expect(deepDiffer(false, 0)).toBe(true);
+    expect(deepDiffer(null, undefined)).toBe(true);
+    expect(deepDiffer(null, 0)).toBe(true);
+    expect(deepDiffer(null, false)).toBe(true);
+    expect(deepDiffer(null, '')).toBe(true);
+    expect(deepDiffer(undefined, 0)).toBe(true);
+    expect(deepDiffer(undefined, false)).toBe(true);
+    expect(deepDiffer(undefined, '')).toBe(true);
+  });
+  it('should diff Objects', () => {
+    expect(deepDiffer({}, {})).toBe(false);
+    expect(deepDiffer({}, null)).toBe(true);
+    expect(deepDiffer(null, {})).toBe(true);
+    expect(deepDiffer({a: 1}, {a: 1})).toBe(false);
+    expect(deepDiffer({a: 1}, {a: 2})).toBe(true);
+    expect(deepDiffer({a: 1}, {a: 1, b: null})).toBe(true);
+    expect(deepDiffer({a: 1}, {a: 1, b: 1})).toBe(true);
+    expect(deepDiffer({a: 1, b: 1}, {a: 1})).toBe(true);
+    expect(deepDiffer({a: {A: 1}, b: 1}, {a: {A: 1}, b: 1})).toBe(false);
+    expect(deepDiffer({a: {A: 1}, b: 1}, {a: {A: 2}, b: 1})).toBe(true);
+    expect(deepDiffer(
+      {a: {A: {aA: 1, bB: 1}}, b: 1},
+      {a: {A: {aA: 1, bB: 1}}, b: 1}
+    )).toBe(false);
+    expect(deepDiffer(
+      {a: {A: {aA: 1, bB: 1}}, b: 1},
+      {a: {A: {aA: 1, cC: 1}}, b: 1}
+    )).toBe(true);
+  });
+  it('should diff Arrays', () => {
+    expect(deepDiffer([], [])).toBe(false);
+    expect(deepDiffer([], null)).toBe(true);
+    expect(deepDiffer(null, [])).toBe(true);
+    expect(deepDiffer([42], [42])).toBe(false);
+    expect(deepDiffer([1], [2])).toBe(true);
+    expect(deepDiffer([1, 2, 3], [1, 2, 3])).toBe(false);
+    expect(deepDiffer([1, 2, 3], [1, 2, 4])).toBe(true);
+    expect(deepDiffer([1, 2, 3], [1, 4, 3])).toBe(true);
+    expect(deepDiffer([1, 2, 3, 4], [1, 2, 3])).toBe(true);
+    expect(deepDiffer([1, 2, 3], [1, 2, 3, 4])).toBe(true);
+    expect(deepDiffer([0, null, false, ''], [0, null, false, ''])).toBe(false);
+    expect(deepDiffer([0, null, false, ''], ['', false, null, 0])).toBe(true);
+  });
+  it('should diff mixed types', () => {
+    expect(deepDiffer({}, [])).toBe(true);
+    expect(deepDiffer([], {})).toBe(true);
+    expect(deepDiffer(
+      {a: [{A: {aA: 1, bB: 1}}, 'bar'], c: [1, [false]]},
+      {a: [{A: {aA: 1, bB: 1}}, 'bar'], c: [1, [false]]}
+    )).toBe(false);
+    expect(deepDiffer(
+      {a: [{A: {aA: 1, bB: 1}}, 'bar'], c: [1, [false]]},
+      {a: [{A: {aA: 1, bB: 2}}, 'bar'], c: [1, [false]]}
+    )).toBe(true);
+    expect(deepDiffer(
+      {a: [{A: {aA: 1, bB: 1}}, 'bar'], c: [1, [false]]},
+      {a: [{A: {aA: 1, bB: 1}}, 'bar'], c: [1, [false], null]}
+    )).toBe(true);
+    expect(deepDiffer(
+      {a: [{A: {aA: 1, bB: 1}}, 'bar'], c: [1, [false]]},
+      {a: [{A: {aA: 1, bB: 1}}, ['bar']], c: [1, [false]]}
+    )).toBe(true);
+  });
+  it('should distinguish between proper Array and Object', () => {
+    expect(deepDiffer(['a', 'b'], {0: 'a', 1: 'b', length: 2})).toBe(true);
+    expect(deepDiffer(['a', 'b'], {length: 2, 0: 'a', 1: 'b'})).toBe(true);
+  });
+  it('should diff same object', () => {
+    var obj = [1,[2,3]];
+    expect(deepDiffer(obj, obj)).toBe(false);
+  });
+});
diff --git a/Libraries/Utilities/differ/deepDiffer.js b/Libraries/Utilities/differ/deepDiffer.js
index 66dc7fa95..4dec6bd7b 100644
--- a/Libraries/Utilities/differ/deepDiffer.js
+++ b/Libraries/Utilities/differ/deepDiffer.js
@@ -35,16 +35,29 @@ var deepDiffer = function(one: any, two: any): bool {
   if (one.constructor !== two.constructor) {
     return true;
   }
-  for (var key in one) {
-    if (deepDiffer(one[key], two[key])) {
+  if (Array.isArray(one)) {
+    // We know two is also an array because the constructors are equal
+    var len = one.length;
+    if (two.length !== len) {
       return true;
     }
-  }
-  for (var twoKey in two) {
-    // The only case we haven't checked yet is keys that are in two but aren't
-    // in one, which means they are different.
-    if (one[twoKey] === undefined && two[twoKey] !== undefined) {
-      return true;
+    for (var ii = 0; ii < len; ii++) {
+      if (deepDiffer(one[ii], two[ii])) {
+        return true;
+      }
+    }
+  } else {
+    for (var key in one) {
+      if (deepDiffer(one[key], two[key])) {
+        return true;
+      }
+    }
+    for (var twoKey in two) {
+      // The only case we haven't checked yet is keys that are in two but aren't
+      // in one, which means they are different.
+      if (one[twoKey] === undefined && two[twoKey] !== undefined) {
+        return true;
+      }
     }
   }
   return false;