function Original() { this.a = 1 }
function NewConstructor() { this.b = 2 }

const obj = new Original();
obj.constructor = NewConstructor; // 修改实例的构造函数引用

function Parent() { this.x = 10 }
function Child() { this.y = 20 }

Child.prototype = new Parent(); // 原型链继承
Child.prototype.constructor = Child; // 修复constructor指向

function DynamicConstructor(type) {
  if (type === 'A') {
    this.value = 'TypeA';
  } else {
    this.value = 'Default';
  }
}

obj instanceof NewConstructor // false

obj.__proto__ = NewConstructor.prototype;

class MyClass {}
MyClass = function() {} // 报错