为什么 super() 返回 es6 中新创建的对象?

Question

据我所知

super([参数]( 关键字调用父构造函数

具有以下基本类：

class X{
constructor(){
return 'x'; // doesn't matter when calling super()
}
}
class Z extends X{
constructor(){
console.log('This will return the newly created object invoked by new keyword', super())
}
}
new Z; // Z {}

为什么super()返回全新的Z对象？

Answer 1

不能从构造函数返回基元类型。

class X{
constructor(){
// to set correct prototype
return Object.setPrototypeOf(new String("x"), new.target.prototype); 
// or 
// return new String('x') just to show you could return any object
}
}
class Z extends X{
constructor(){
console.log('This will return the newly created object invoked by new keyword', super())
}
}
console.log(new Z); // Z {}