javascript - Lodash _.result() 默认值

Question

为什么 lodash 没有 result方法在这种情况下返回默认值？

Arguments object (Object): The object to query.

key (string): The key of the property to resolve.

[defaultValue] (*): The value returned if the property value resolves to undefined.

var result = _.result({ foo: 1 }, 'bar', 'default');

console.log(typeof _.result({ foo: 1 }, 'bar') === 'undefined') // true

console.log(result); // expected: 'default'

http://jsfiddle.net/dbvs5ney/

Answer 1

default参数好像是3.0.0版本才加入的
比较_.result实现:
3.0.0 lodash.js

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;
}

和2.2.1 lodash.js :

function result(object, property) {
  if (object) {
    var value = object[property];
    return isFunction(value) ? object[property]() : value;
  }
}