javascript - 为什么我的函数无法访问 Nodejs 中的全局对象

Question

在浏览器中执行此函数时，我收到正确且预期的消息

function displayInformation() {
  console.log("student with " + this.rollNo + " is " + this.name + " who is in class: " + this.class + " and he is of " + this.subject + " stream ")
};

var student1 = {
  rollNo: 100,
  name: "Rajiv",
  class: 10,
  subject: "PCMC",
  display: displayInformation
};

var student2 = {
  rollNo: 101,
  name: "Sam",
  class: 11,
  subject: "PCMB",
  display: displayInformation
};

var student3 = {
  rollNo: 102,
  name: "Ghanshyam",
  class: 12,
  subject: "commerce",
  display: displayInformation
};

student1.display();
student2.display();
student3.display();

this.name = "Raju";
this.age = 28;
this.rollNo = 103;
this.class= 123;
this.subject = "Arts";

displayInformation();

但是，当在 Nodejs 中执行此代码时，我在最后一句中得到 undefined:

student with 100 is Rajiv who is in class: 10 and he is of PCMC stream
student with 101 is Sam who is in class: 11 and he is of PCMB stream
student with 102 is Ghanshyam who is in class: 12 and he is of commerce stream
student with undefined is undefined who is in class: undefined and he is of undefined stream

为什么 Nodejs 和浏览器中的结果不一样？

Answer 1

最后一行实际结果是:

student with 103 is Raju who is in class: undefined and he is of Arts stream 

未定义是因为您没有为this.class赋值

function displayInformation() {
  console.log("student with " + this.rollNo + " is " + this.name + " who is in class: " + this.class + " and he is of " + this.subject + " stream ")
};

this.name = "Raju";
this.age = 28;
this.rollNo = 103;
this.subject = "Arts";
this.class = 123; // <-- You missed this

displayInformation();

另外，我真的建议不要使用 this 全局对象，我不确定你为什么使用它。