for ...在键值中实例化对象，而不是JavaScript中的forEach

Question

有什么办法可以在键值实例对象中代替forEach ？ 使用forEach对我来说很容易，但我正在寻找for ... in。

我做到了每个：

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

这种方式有效，但是我需要了解它的工作原理。

Answer 1

请尝试以下操作：

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);