JavaScript ---- Types
1. JavaScript types can be divided into two categories:
     1.1 primitive types
     1.2 object types

2. JavaScript's primitive types include:
     2.1 numbers
     2.2 strings of text (known as strings)
     2.3 Boolean truth values(known as booleans)
     2.4 null and undefined

3. Any JavaScript value that is not a number, a string, a boolean, or null or undefined is an object.
   An object(that is, a member of the type object) is a collection of properties where each property has a name and a value(either a primitive value, such as a number or string, or an object).
   An ordinary JavaScript object is an unordered collection of named values.The language also defines a special kind of object, known as an array, that represents an ordered collection of numbered values.
   JavaScript defines another special kind of object, known as a function. A function is an object that has executable code associated with it.

4. The Date class defines objects that represent dates.
   The RegExp class defines objects that represent regular expressions.
   The Error class defines objects that represent syntax and runtime errors that can occur in a JavaScript program.

5. Numbers, booleans, Strings, null, and undefined are immutable
   Objects and arrays are mutable