Programming Fundamentals:
=========================
1) Keywords:
============
==> also called as "Reserved words" or "built-in" words.
	have a pre-defined meaning
==> 66-keywords
==> Keywords are always write/use in lower case only.

2) Identifiers:
===============
==> to name any entity/element of the program in JavaScript, we need an Identifier.

Identifier Rules/Naming Conventions:
=====================================
1) Identifier should include with:
	Alphabets (Upper-case/Lower-case/Any Case)
	Digits (0 to 9)
	Two Special characters:
		Underscore sign ==> _
		Dollar Sign ==> $

Ex: a = 10
a_23 = 12.23
a.c = 123 ==> Invalid

2) Identifier never start with digit
	but can allowed to start other than the digit.
ex: 97rk = 123 ==> error
rk97 = 1.23
_97rk = 0.009
$rk_12 = 123

3) No other symbols are allowed in identifier.
4) No keywords of JS can use as an Identifier.
5) JS is Case Sensitive Programming Language.
6) 

Ecommerce Application ==> XYZ ltd

specification book


a = 112;
// b#c = 221;
$97rk = 1122
a97 = 121;
// if = 123;
If = 123;
IF = 1.23;
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = 100

console.log(a);
// console.log(b#c)
console.log($97rk);
console.log(a97);
console.log(If);
console.log(IF);
console.log(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa);

==============================================================
Variables:
==========
==> is a named memory or a container
	can be used to store values

a = 10
a = 100
a = 200

==> In JavaScript, the variable can be defined in different ways:

using "var" keyword
===================
Syntax:
	var identifier = value;

console.log(a); // due to the hoisting, we can access the variable with var keyword before the declaration.

var a;  // initialization


console.log(a);
console.log(c);
{
    var a = 10;//block variables/Local Variables
    var b = 20;
    var c = a + b;
    console.log(c);

    // Local variable/Block variable can be with "var" keyword can able to access within the same block and outside of the block also.

}

console.log(c);
{
    console.log(c);

    // if the variable with "var" keyword, we can access the variable of one block in another block. 
}