1  var copyObject = require('./_copyObject'),
 2      createAssigner = require('./_createAssigner'),
 3      keysIn = require('./keysIn');
 4  
 5  /**
 6   * This method is like `_.assignIn` except that it accepts `customizer`
 7   * which is invoked to produce the assigned values. If `customizer` returns
 8   * `undefined`, assignment is handled by the method instead. The `customizer`
 9   * is invoked with five arguments: (objValue, srcValue, key, object, source).
10   *
11   * **Note:** This method mutates `object`.
12   *
13   * @static
14   * @memberOf _
15   * @since 4.0.0
16   * @alias extendWith
17   * @category Object
18   * @param {Object} object The destination object.
19   * @param {...Object} sources The source objects.
20   * @param {Function} [customizer] The function to customize assigned values.
21   * @returns {Object} Returns `object`.
22   * @see _.assignWith
23   * @example
24   *
25   * function customizer(objValue, srcValue) {
26   *   return _.isUndefined(objValue) ? srcValue : objValue;
27   * }
28   *
29   * var defaults = _.partialRight(_.assignInWith, customizer);
30   *
31   * defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
32   * // => { 'a': 1, 'b': 2 }
33   */
34  var assignInWith = createAssigner(function(object, source, srcIndex, customizer) {
35    copyObject(source, keysIn(source), object, customizer);
36  });
37  
38  module.exports = assignInWith;