js 判断实例化

object instanceof constructor

// 定义一个构造函数
function Person(name, age) {
  this.name = name;
  this.age = age;
}

// 创建一个Person的实例
var john = new Person("John", 30);

// 使用instanceof判断john是否是Person的实例
console.log(john instanceof Person); // 输出: true

// 创建一个普通的对象
var obj = { name: "Alice", age: 25 };

// 使用instanceof判断obj是否是Person的实例
console.log(obj instanceof Person); // 输出: false

function getType(obj) {
  return Object.prototype.toString.call(obj).slice(8, -1);
}

console.log(getType(john)); // 输出: "Object"
console.log(getType(new Date())); // 输出: "Date"

console.log(john.constructor === Person); // 输出: true

class Person {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

const john = new Person("John", 30);
console.log(john instanceof Person); // 输出: true