javascript - 对象中的 getFullYear()

Question

这个问题已经有答案了:

Access object properties within object [duplicate] (2 个回答)

已关闭 6 年前。

谁能解释一下为什么这不起作用:

var todayDate = new Date();
var todayYear = todayDate.getFullYear();

var User = {
  firstName: "John",
  lastName: "Doe",
  email: "email@email.com",
  dob: new Date(85, 1, 1),
  userBirthYear: dob.getFullYear(),
  age: todayYear - userBirthYear,
  url: "http://www.google.com",
  bio: "I love pizza",
  interests: ["food", "NBA", "movies"]
}

userBirthYear似乎没有初始化。如果我移动 userBirthYear在对象之外作为单独的变量，它工作得很好。

Answer 1

dob 不是变量，它是 User 对象的属性。

但是在编译整个对象之前，您无法直接访问对象属性

你可以这样做；

var User = {
  firstName: "John",
  lastName: "Doe",
  email: "email@email.com",
  dob: new Date(85, 1, 1), 
  age: todayYear - userBirthYear,
  url: "http://www.google.com",
  bio: "I love pizza",
  interests: ["food", "NBA", "movies"]
}
// User object now exists, modify it any way you need
 User.userBirthYear = User.dob.getFullYear();