instanceof 运算符​用于检测构造函数的 ​​prototype​​ 属性是否出现在某个实例对象的原型链上。

function Car(make, model, year) {
  this.make = make;
  this.model = model;
  this.year = year;
}
const auto = new Car('Honda', 'Accord', 1998);

console.log(auto instanceof Car);
// expected output: true

console.log(auto instanceof Object);
// expected output: true