TypexJS naming scheme applies to all primitive immutable types:

• Null
• Undefined
• Boolean
• Number
• BigInt
• String
• Array
• Object
• Symbol

It extends to specific Object types:

• Class
• RegExp
• Function

The suffix specifying the type is an underscore character followed by a single letter:

• lowercase for “wrapped” types Boolean, Number, String, Array, Object, Symbol, Function, Class, RegExp. BigInt type is listed in the number page. See MDN Primitive description ,
• uppercase for “unwrapped” types Null, Undefined.

Type	Suffix
Null	_N
Undefined	_U
Boolean	_b
Number	_n
String	_s
Array	_a
Object	_o
Symbol	_y
Class	_c
RegExp	_r

To convey even more meaningful information, function identifiers follow a slightly different scheme:

• two underscore characters before the type specifier of the returned value. Consequently, if a function doesn’t return anything void function , we use the v letter for its suffix a possible alternative is to use the undefined value: U .

Function return is	Suffix
Null	__N
Undefined	__U
Boolean	__b
Number	__n
String	__s
Array	__a
Object	__o
Symbol	__y
Class	__c
RegExp	__r
Function	__f
Void	__v

const awesome__s = () => 'An awesome String'
const clone__s = awesome__s

In case of a function returning different types of value, we just omit the type character.

const silly__ = string_b => string_b ? 'A weird String' : 1234

We could do the same for a variable accepting different kinds of type, but is it really a good practice?

let hybrid_ = 'A String'
hybrid_ = 1234 //: What a mess!