javascript - 尝试实现构造函数模式javascript

Question

我得到的值是未定义的，即使它已被填充。我想我已经填充了它，但感觉对象的实例出了问题。如果有人能解释我哪里出错了，那就太好了。

function Student(fn, sn, a, d)
{
  this.firstName = fn;
  this.lastName = sn;
  this.age = a;
  this.degree = d;
  this.displayStudent = displayStudent;
}

function displayStudent()
{
  console.log(this.fn);
  console.log(this.sn);
  console.log(this.a);
  console.log(this.d);
}

var studentObj = new Student("d", "r", 20,
                         "bachelors of science");
studentObj.displayStudent();

Answer 1

我认为这只是一个错字，你的代码应该是这样的:

function Student(fn, sn, a, d)
{
  this.firstName = fn;
  this.lastName = sn;
  this.age = a;
  this.degree = d;
  this.displayStudent = displayStudent;
}

function displayStudent()
{
  console.log(this.firstName);
  console.log(this.lastName);
  console.log(this.age);
  console.log(this.degree);
}

var studentObj = new Student("d", "r", 20,
                         "bachelors of science");
studentObj.displayStudent();

在您的代码中，您尝试打印 Student 的“构造函数”属性而不是您设置的 Student 的“对象”参数。