- typeof能识别值的类型;string、number、null、undefined、boolean、obejct、function、symbol、bigint
- instanceof用于检测构造函数的
prototype
是否出现在对象的原型链上
const foo = "abc"; console.log(tyepof foo); // 'string' const foo2 = 123; console.log(tyepof foo2); // 'number' function Bar(){} const bar = new Bar(); console.log(bar instanceof Bar);// true const obj = new Object(); console.log(obj instanceof Bar);// false