1  var isObject = require('./isObject'),
 2      isPrototype = require('./_isPrototype'),
 3      nativeKeysIn = require('./_nativeKeysIn');
 4  
 5  /** Used for built-in method references. */
 6  var objectProto = Object.prototype;
 7  
 8  /** Used to check objects for own properties. */
 9  var hasOwnProperty = objectProto.hasOwnProperty;
10  
11  /**
12   * The base implementation of `_.keysIn` which doesn't treat sparse arrays as dense.
13   *
14   * @private
15   * @param {Object} object The object to query.
16   * @returns {Array} Returns the array of property names.
17   */
18  function baseKeysIn(object) {
19    if (!isObject(object)) {
20      return nativeKeysIn(object);
21    }
22    var isProto = isPrototype(object),
23        result = [];
24  
25    for (var key in object) {
26      if (!(key == 'constructor' && (isProto || !hasOwnProperty.call(object, key)))) {
27        result.push(key);
28      }
29    }
30    return result;
31  }
32  
33  module.exports = baseKeysIn;