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+/**
+ * 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.
+ *
+ * @typechecks
+ *
+ */
+
+/*eslint-disable no-self-compare */
+
+'use strict';
+
+var hasOwnProperty = Object.prototype.hasOwnProperty;
+
+/**
+ * inlined Object.is polyfill to avoid requiring consumers ship their own
+ * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is
+ */
+function is(x, y) {
+ // SameValue algorithm
+ if (x === y) {
+ // Steps 1-5, 7-10
+ // Steps 6.b-6.e: +0 != -0
+ // Added the nonzero y check to make Flow happy, but it is redundant
+ return x !== 0 || y !== 0 || 1 / x === 1 / y;
+ } else {
+ // Step 6.a: NaN == NaN
+ return x !== x && y !== y;
+ }
+}
+
+/**
+ * Performs equality by iterating through keys on an object and returning false
+ * when any key has values which are not strictly equal between the arguments.
+ * Returns true when the values of all keys are strictly equal.
+ */
+function shallowEqual(objA, objB) {
+ if (is(objA, objB)) {
+ return true;
+ }
+
+ if (typeof objA !== 'object' || objA === null || typeof objB !== 'object' || objB === null) {
+ return false;
+ }
+
+ var keysA = Object.keys(objA);
+ var keysB = Object.keys(objB);
+
+ if (keysA.length !== keysB.length) {
+ return false;
+ }
+
+ // Test for A's keys different from B.
+ for (var i = 0; i < keysA.length; i++) {
+ if (!hasOwnProperty.call(objB, keysA[i]) || !is(objA[keysA[i]], objB[keysA[i]])) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+module.exports = shallowEqual; \ No newline at end of file