object/result.js

define(['../lang/isFunction'], function(isFunction) {

  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
  var undefined;

  /**
   * Resolves the value of property `key` on `object`. If the value of `key` is
   * a function it is invoked with the `this` binding of `object` and its result
   * is returned, else the property value is returned. If the property value is
   * `undefined` the `defaultValue` is used in its place.
   *
   * @static
   * @memberOf _
   * @category Object
   * @param {Object} object The object to query.
   * @param {string} key The key of the property to resolve.
   * @param {*} [defaultValue] The value returned if the property value
   *  resolves to `undefined`.
   * @returns {*} Returns the resolved value.
   * @example
   *
   * var object = { 'user': 'fred', 'age': _.constant(40) };
   *
   * _.result(object, 'user');
   * // => 'fred'
   *
   * _.result(object, 'age');
   * // => 40
   *
   * _.result(object, 'status', 'busy');
   * // => 'busy'
   *
   * _.result(object, 'status', _.constant('busy'));
   * // => 'busy'
   */
  function result(object, key, defaultValue) {
    var value = object == null ? undefined : object[key];
    if (typeof value == 'undefined') {
      value = defaultValue;
    }
    return isFunction(value) ? value.call(object) : value;
  }

  return result;
});