javascript - 未捕获的类型错误 : undefined is not a function

Question

我是一名相当初级的程序员，所以如果这个问题的解决方案相当简单，请原谅我(尽管我已经努力寻找已经发布的解决方案)。我正在尝试面向对象编程，但在第 14 行运行程序“Uncaught TypeError: undefined is not a function”时收到此错误消息。

var Gladiator = Object.create(null);
Gladiator.prototype = {
  becomeGladiator: function(attack, defense, hitPoints, name) {
    this.attack = attack;
    this.defense = defense;
    this.hitPoints = hitPoints;
    this.name = name;
  },
};

var Human = Object.create(Gladiator.prototype); 
Human.prototype = {
  becomeHuman: function(attack, defense, hitPoints, name) {
    this.becomeGladiator(attack, defense, hitPoints, name); //Error here
};
var ethan = Object.create(Human.prototype);
ethan.becomeHuman(14, 12, 15, "Ethan")

谢谢。

Answer 1

prototype 是函数(构造函数)的一个属性，用于在创建实例时设置内部 [[Prototype]] 属性。 Object.create 接受一个父对象并创建一个原型(prototype)为父对象的对象；你只需要简单的对象:

var Gladiator = Object.create(null);
Gladiator.becomeGladiator = function(attack, defense, hitPoints, name) {
  this.attack = attack;
  this.defense = defense;
  this.hitPoints = hitPoints;
  this.name = name;
};

var Human = Object.create(Gladiator);
Human.becomeHuman = function(attack, defense, hitPoints, name) {
  this.becomeGladiator(attack, defense, hitPoints, name); //Error here
};

var ethan = Object.create(Human);
ethan.becomeHuman(14, 12, 15, "Ethan");