var o1 = new Object()
o1.__proto__ // [Object: null prototype] {}
typeof o1.__proto__ // 'object'
o1.prototype // undefined

Object.prototype // [Object: null prototype] {}

function Foo() {}
Foo.prototype // {}
Foo.f1 = () => {return 1} // [Function (anonymous)]
Foo.prototype // {}
function Bar() { this.x=1;this.y=function(){return 'y'} }

Bar.prototype // {}
Bar.prototype.x //undefined
> Bar.prototype === Foo.prototype
false
> Bar.prototype == Foo.prototype
false
> var bar1 = new Bar()
undefined
> bar1.__proto__
{}
> bar1.__proto__ === Bar.prototype
true
> Foo.prototype.x = 1
1
> var foo1 = new Foo()
undefined
> foo1.x
1
> function FooFoo() {}
undefined
> FooFoo.prototype.xx = 2
2
> FooFoo.prototype.__proto__ = Foo.prototype
{ x: 1 }
> var foofoo1 = new FooFoo()
undefined
> foofoo1.x

事件循环

https://www.cnblogs.com/lideyao/p/12022717.html