__proto__ vs prototype!

__proto__

• Each object has a property '__proto__'
• __proto__ is a private system property
• When accessing the property of an object, it is first searched in this object:
  if false: it searched in __proto__:
      if false: it searched in __proto__.__proto__ and so on
• __proto__ of every value (but not null and underfined) refers to prototype of it's data type:

(0).__proto__ === Number.prototype &&
false.__proto__ === Boolean.prototype &&
"string".__proto__ === String.prototype &&
(new Date).__proto__ === Date.prototype &&
(function(){}/* new Function */).__proto__ === Function.prototype

All data types inherits from Object:

Number.prototype.__proto__ === Object.prototype

But only Object has no prototype:

Object.prototype.__proto__ === null

prototype

• This is a common property except for two nuances:
• Only functions in JavaScript have a prototype property. It defaults to the object with a single property constructor, which refers to the function itself.
• Prototype property is used to create new objects using operator 'new'.

* this article is partial translate of Original article