dario@win11 MINGW64 ~
$ node
Welcome to Node.js v20.13.1.
Type ".help" for more information.

> typeof 10
'number'
> typeof 3.14
'number'

> typeof true
'boolean'
> typeof false
'boolean'

> typeof "abc"
'string'

> typeof null
'object'
> typeof [1,2,3]
'object'
> typeof { "key1" : 1 , "key2" : 2 }
'object'
>

https://en.wikipedia.org/wiki/JSON
https://it.wikipedia.org/wiki/JavaScript_Object_Notation