lodash-es/_baseKeysIn.js

import Reflect from './_Reflect';
import iteratorToArray from './_iteratorToArray';

/** Used for built-in method references. */
var objectProto = Object.prototype;

/** Built-in value references. */
var enumerate = Reflect ? Reflect.enumerate : undefined,
    propertyIsEnumerable = objectProto.propertyIsEnumerable;

/**
 * The base implementation of `_.keysIn` which doesn't skip the constructor
 * property of prototypes or treat sparse arrays as dense.
 *
 * @private
 * @param {Object} object The object to query.
 * @returns {Array} Returns the array of property names.
 */
function baseKeysIn(object) {
  object = object == null ? object : Object(object);

  var result = [];
  for (var key in object) {
    result.push(key);
  }
  return result;
}

// Fallback for IE < 9 with es6-shim.
if (enumerate && !propertyIsEnumerable.call({ 'valueOf': 1 }, 'valueOf')) {
  baseKeysIn = function(object) {
    return iteratorToArray(enumerate(object));
  };
}

export default baseKeysIn;