javascript - 未捕获的类型错误 : Class constructor Hero cannot be invoked without 'new'

Question

回顾这个伟大的tutorial: Understanding Classes in JavaScript作者:Tania Rascia，我在查看如何操作时遇到了此错误 extend a class .

class Hero {
  constructor(name, level) {
    this.name = name
    this.level = level
  }

  // Adding a method to the constructor
  greet() {
    return `${this.name} says hello.`
  }
}

// Creating a new constructor from the parent
function Mage(name, level, spell) {
  // Chain constructor with call
  Hero.call(this, name, level)

  this.spell = spell
}

VM3527:4 Uncaught TypeError: Class constructor Hero cannot be invoked without 'new' at new Mage (:4:8) at :1:15

当使用不带 class 关键字的函数时，此将按预期工作。

function Hero(name, level) {
  this.name = name;
  this.level = level;
}

Answer 1

由于错误消息是对其自身的描述，因此如果不尝试创建它的新实例，就无法调用构造函数。

var myHeor = new Hero(name, level);

无需创建实例即可调用的唯一方法是 static方法