Every Object is a function and every function is Object

 

I was reading this link JavaScript_syntax

This seems to be cyclic - that every function is an Object and every Object itself is a function. Which is the atomic one? Can someone explain in a better way?

  • Anything that is not a primitive type (undefined, null, number, string, boolean) is an object (or an instance) in JavaScript. That means function inherits from object .

  • Object instances can contain more instances which can be functions. That's what we call a "method" (since it has an automatic this variable).

  • Since you can't "call" every Object instance, not every object is a function.

    • Every function is an object. Objects can contain functions (methods) but an object is not necessary a function.

    I think this concept is often misunderstood.

    A utility to visualize JS types relationship http://jstype.herokuapp.com/#/home

    Javascript Data Types

  • Primitive types - numbers, strings, booleans, null and undefined.
  • All non-primitive types are object : 

    • var foo = { }; 
var foo = [1, 2, 3]; 
var foo = function abc() { return "hello world"; }; 
var foo = new Number(30); 
var foo = new String("Hello World"); 
var foo = new Boolean(true); 
var foo = new RegExp(/[foo]+/);

// All 'foo` are object.
    链接地址: http://www.djcxy.com/p/76346.html

    上一篇: JavaScript：if（！x）`和if（x == null）`有什么区别？

    下一篇: 每个对象都是一个函数，每个函数都是对象