Short answer

As far as data types are concerned, in JavaScript there are two basic classes, primitives and objects, so not everything is an object in JavaScript , but beware, this might turn primitives into an object temporarily.

Demonstration

Explanation

With code

instanseofis an operator to test whether the first operand, an object, is an instance of the second, a constructor. It follows the whole chain of prototypes, if it finds it it returns true, if it doesn't find it it returns false.

console.log(1 instanceof Object); //Devuelve false
console.log(Object(1) instanceof Object); //Devuelve true

Based on the documentation

The following is a statement from the Mozilla Developer Network glossary, which very briefly clarifies that not everything in JavaScript is an object , my emphasis.

Primitive _

A primitive (value primitive, data type primitive) is data that is not an object and has no methods. In JavaScript there are 6 primitive data types: string , number , boolean , null , undefined , symbol (new in ECMAScript 2015).

Of Grammar and Types

Boolean literals

Boolean type literals have 2 possible values: true and false.

DO NOT confuse the Boolean primitive values ​​true and false with the true and false values ​​of the Boolean Object. The Boolean object is a wrapper around the Boolean Primitive data type. For more information check Boolean .

String literals

A String literal corresponds to Zero or more characters, enclosed within double (") or single (') quotes. A string must be delimited by quotes of the same type; this means that both are always double or single in each of The following are examples of String literals:

• "foo"
• 'bar'
• "1234"
• "One line \n another line"
• "John's Cat"

You can use any of the String object's methods on a string literal—JavaScript automatically converts the string literal to a String object temporarily, calls the method, and finally destroys the temporary String object. You can also use the String.length property with a string literal:

Below what I think are the sections of the ECMAScript 2016 (Version 7) that clarify this

§4.3.2 primitive value

member of one of the types Undefined, Null, Boolean, Number, Symbol, or String as defined in clause 6

NOTE
A primitive value is a datum that is represented directly at the lowest level of the language implementation.

§4.3.3 objects

member of the type Object

NOTE
An object is a collection of properties and has a single prototype object. The prototype may be the null value.

Note that an object is not at the lowest level of the language implementation, unlike primitives.

Full explanation about data types and values ​​in ECMAScript 2016 (version 7) is in §6 ECMAScript Data Types and Values

• Boolean Primitives vs. Boolean Object