shallowEqual.js

/**
 * Copyright 2013-2014, 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.
 *
 * @providesModule shallowEqual
 */

"use strict";

/**
 * Performs equality by iterating through keys on an object and returning
 * false when any key has values which are not strictly equal between
 * objA and objB. Returns true when the values of all keys are strictly equal.
 *
 * @return {boolean}
 */
function shallowEqual(objA, objB) {
  if (objA === objB) {
    return true;
  }
  var key;
  // Test for A's keys different from B.
  for (key in objA) {
    if (objA.hasOwnProperty(key) &&
        (!objB.hasOwnProperty(key) || objA[key] !== objB[key])) {
      return false;
    }
  }
  // Test for B's keys missing from A.
  for (key in objB) {
    if (objB.hasOwnProperty(key) && !objA.hasOwnProperty(key)) {
      return false;
    }
  }
  return true;
}

module.exports = shallowEqual;