for...in 键值实例对象而不是 JavaScript 中的 forEach

Question

有没有什么方法可以代替forEach 使用 for...in 键值实例对象？使用forEach 对我来说很容易，但我正在寻找使用 for...in 来实现它。

我为每个人都做了这个：

function Person(fullName, gender, city) {
    this.fullName = fullName;
    this.gender = gender;
    this.city = city;
}

var person01 = new Person("Nancy", "Female", "Los Angeles");
var person02 = new Person("James", "Male", "New York");
var person03 = new Person("Lucia", "Female", "Santa Barbara");


//To do the loop
var persons = [
    {fullName: "Nancy", gender: "Female", city: "Los Angeles"},
    {fullName: "James", gender: "Male", city: "New York"},
    {fullName: "Lucia", gender: "Female", city: "Santa Barbara"},
]

function listNames(myObject) {

    persons.forEach(function(obj) {
        console.log(obj.fullName);  
    });
}

listNames(persons);
//Nancy, James, Lucia

这种方式可行，但我需要了解它的工作原理。

Answer 1

尝试以下方法：

for(var key in myObject){
  console.log(myObject[key].fullName);
}

工作示例：

function Person(fullName, gender, city) {
    this.fullName = fullName;
    this.gender = gender;
    this.city = city;
}

var person01 = new Person("Nancy", "Female", "Los Angeles");
var person02 = new Person("James", "Male", "New York");
var person03 = new Person("Lucia", "Female", "Santa Barbara");


//To do the loop
var persons = [
    {fullName: "Nancy", gender: "Female", city: "Los Angeles"},
    {fullName: "James", gender: "Male", city: "New York"},
    {fullName: "Lucia", gender: "Female", city: "Santa Barbara"},
]

function listNames(myObject) {
  for(var key in myObject){
    console.log(myObject[key].fullName);
  }
}

listNames(persons);