Question

任何人都可以解释为什么这不起作用：

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。如果我将对象外部的userBirthYear作为单独的变量移动，它可以正常工作。

Answer 1

dob不是变量，它是User对象的属性。

但是在编译完整个对象之前，你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();

对象中的getFullYear（）

1 个答案: