javascript - 从函数构造函数访问方法

Question

retirementAge方法如何访问同一个Person函数构造函数中的calculateAge方法的值？

var Person = function(name, job, yearOfBirth) {
  this.name = name;
  this.yearOfBirth = yearOfBirth;
  this.calculateAge = function() {
    console.log(2018 - this.yearOfBirth)
  };
  this.retirementAge = function(el) {
    console.log(66 - this.calculateAge)
  }
}

var john = new Person('John', 'teacher', 1998);
john.retirementAge(john.calculateAge());

Answer 1

如果您想通过调用来获取值，则需要从 this.calculateAge 返回一个值。当您这样做时，您只需调用函数 this.calculateAge() 即可，它应该按预期工作:

let Person = function(name, job, yearOfBirth) {
  this.name = name;
  this.yearOfBirth = yearOfBirth;
  this.calculateAge = function() {
    return 2018 - this.yearOfBirth
  };
  this.retirementAge = function(el) {
    return 66 - this.calculateAge()
  }
}

var john = new Person('John', 'teacher', 1998);
console.log("Age:", john.calculateAge())
console.log("Years to retirement:", john.retirementAge())