Javascript Types

We can categorize Javascript data types in different ways.

Category I

• Primitive Types 

Numbers, strings, booleans, null, undefined

• Object Types

Everything other than the above, including regular object and special kinds of object (Array, Function, Date, RegExp, Error)

Category II

• Have Methods

Objects, numbers, strings and boolean (numbers, strings and booleans behave as if they had methods)

• Don't Have Methods

null and undefined

Category III

• Immutable 

Numbers, boolean, null, undefined, strings (different from Ruby, in which string is mutable)

• Mutable

Objects and arrays