为什么 instanceof 运算符在确定对象类型时比构造函数 属性 更安全？

Question

当作者说：

The constructor property was originally intended for use in identifying the object type. However, the instanceof operator is considered to be a safer way of determining type

你能解释一下不使用 constructor 而不是 instanceof 来确定对象类型背后的问题是什么吗？

没有区别的传统示例可能是这样的：

car instanceof Car  // true
car.constructor === Car // true

谢谢...

Answer 1

class A {

}

class B extends A {

}

var x = new B();

console.log('instanceof A', x instanceof A);
console.log('instanceof B', x instanceof B);
console.log('constructor = A', x.constructor === A);
console.log('constructor = B', x.constructor === B);

子类化有所作为