/**

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 *

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

 *

 * @flow

 */

import is from './objectIs';

import hasOwnProperty from './hasOwnProperty';

/**

 * 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: mixed, objB: mixed): boolean {

  if (is(objA, objB)) {

    return true;

  }

  if (

    typeof objA !== 'object' ||

    objA === null ||

    typeof objB !== 'object' ||

    objB === null

  ) {

    return false;

  }

  const keysA = Object.keys(objA);

  const keysB = Object.keys(objB);

  if (keysA.length !== keysB.length) {

    return false;

  }

  // Test for A's keys different from B.

  for (let i = 0; i < keysA.length; i++) {

    const currentKey = keysA[i];

    if (

      !hasOwnProperty.call(objB, currentKey) ||

      // $FlowFixMe[incompatible-use] lost refinement of `objB`

      !is(objA[currentKey], objB[currentKey])

    ) {

      return false;

    }

  }

  return true;

}

export default shallowEqual;