如何为函数添加方法？答案

【问题标题】：How add method to a function?如何为函数添加方法？
【发布时间】：2018-03-21 23:21:10
【问题描述】：

我在这个练习中遇到过，但我不知道如何解决 CHALLENGE 3。

/*Create a function PersonConstructor that uses the this keyword to save a single property onto its scope called
     greet. greet should be a function that logs the string 'hello'.*/
function PersonConstructor() {
  this.greet = function() {
    console.log('hello!');
  }
}

var simon = new PersonConstructor;

simon.greet(); // -> Logs 'hello'

/*** CHALLENGE 2 of 3 ***/
/*Create a function personFromConstructor that takes as input a name and an age. When called, the function will create
 person objects using the new keyword instead of the Object.create method.*/

function personFromConstructor(name, age) {
  var personObj = new PersonConstructor;
  personObj.name = name;
  personObj.age = age;
  return personObj;
}

var mike = personFromConstructor('Mike', 30);

console.log(mike.name); // -> Logs 'Mike'
console.log(mike.age); //-> Logs 30
mike.greet(); //-> Logs 'hello'

/*** CHALLENGE 3 of 3 ***/
/*Without editing the code you've already written, add an introduce method to the PersonConstructor function that logs
 "Hi, my name is [name]".*/
PersonConstructor.introduce = function() {
  console.log("Hi, my name is ");
};
mike.introduce(); // -> Logs 'Hi, my name is Mike' // doesn't work

如何在函数 PersonConstructor 中添加方法？ mike.introduce() 应该记录 // -> 记录“嗨，我叫 Mike”

【问题讨论】：

您是否尝试将其添加到对象的原型中？即PersonConstructor.prototype.introduce = function() {，然后是console.log("Hi, my name is" + this.name)
@activedecay 没关系
@seesharper 没关系，但需要大量编辑才能使其清晰易读。我为什么要读 cmets？

标签： javascript oop methods

【解决方案1】：

您需要将函数添加到类的原型中，这样它将适用于所有对象。它可以使用this.name 来访问对象的属性。

/*Create a function PersonConstructor that uses the this keyword to save a single property onto its scope called
     greet. greet should be a function that logs the string 'hello'.*/
function PersonConstructor() {
  this.greet = function() {
    console.log('hello!');
  }
}

var simon = new PersonConstructor;

simon.greet(); // -> Logs 'hello'

/*** CHALLENGE 2 of 3 ***/
/*Create a function personFromConstructor that takes as input a name and an age. When called, the function will create
 person objects using the new keyword instead of the Object.create method.*/

function personFromConstructor(name, age) {
  var personObj = new PersonConstructor;
  personObj.name = name;
  personObj.age = age;
  return personObj;
}

var mike = personFromConstructor('Mike', 30);

console.log(mike.name); // -> Logs 'Mike'
console.log(mike.age); //-> Logs 30
mike.greet(); //-> Logs 'hello'

/*** CHALLENGE 3 of 3 ***/
/*Without editing the code you've already written, add an introduce method to the PersonConstructor function that logs
 "Hi, my name is [name]".*/
PersonConstructor.prototype.introduce = function() {
  console.log("Hi, my name is " + this.name);
};
mike.introduce(); // -> Logs 'Hi, my name is Mike' // doesn't work

【讨论】：