版权声明：个人笔记，不喜勿喷 https://blog.csdn.net/qq_39571197/article/details/88575251
const A = function(){};
A.__proto__ = undefined; // or null
A.prototype = undefined; // or null
console.log(A); // ƒ #<Function>
const a = new A();
console.log(a.__proto__ === Object.prototype); // true