How do I know when the prototype chain ends?

In the first case, the prototype chain is longer than in the second one.

function Func() {};
Func.__proto__ == Function.prototype; //true
Func.__proto__.__proto__ == Object.prototype; //true
Func.__proto__.__proto__.__proto__ == Object.prototype; //false
Func.__proto__.__proto__.__proto__.__proto__ == Object.prototype; //Cannot read property '__proto__' of null

In the second case, it's shorter.

let obj = {};
    obj.__proto__ == Object.prototype; //true
    obj.__proto__.__proto__ == Object.prototype; //false
    obj.__proto__.__proto__.__proto__ == Object.prototype; //Cannot read property '__proto__' of null

Why? The line of the second example obj .__ proto __.__ proto__ == Object.prototype gives false. But in the first case, the similar line of code Func .__ proto __.__ proto__ == Object.prototype gives true.

What's the difference? Why does the first example have longer prototype chain than the second one? What does it depend on?

Solution

Functions are also Objects in Javascript. Thinking of it as levels, they are one level below Object in the chain/tree.

So if any function is defined, its __proto__ will be Function.prototype. Function.prototype's __proto__ will be Object.prototype.

Note: When we do let obj ={}, under the hood obj is created as an instance of Object. Any instance of Object will have its __proto__ set to Object.prototype.