创建实例时出错
重要性：5
以下是 Rabbit 扩展 Animal 的代码。
不幸的是，无法创建 Rabbit 对象。问题出在哪里？请修复它。
class Animal {
constructor(name) {
this.name = name;
}
}
class Rabbit extends Animal {
constructor(name) {
this.name = name;
this.created = Date.now();
}
}
let rabbit = new Rabbit("White Rabbit"); // Error: this is not defined
alert(rabbit.name);这是因为子构造函数必须调用 super()。
以下是更正后的代码
class Animal {
constructor(name) {
this.name = name;
}
}
class Rabbit extends Animal {
constructor(name) {
super(name);
this.created = Date.now();
}
}
let rabbit = new Rabbit("White Rabbit"); // ok now
alert(rabbit.name); // White Rabbit