Identifiers:
Identifiers are the names given to variables,functions etc..

• Identifiers are case sensitive.
• keywords are not used as identifiers.
• The first character should not be a number.
• The first keyword can be an alphabet,underscore or dollar.
• No special characters are allowed except dollar and underscore.
• variables are used to store the data values.
• javascript uses the var keyword to declare variables.
• Rules to declare variables.

Literals:

Literals are used to represent values.These values are fixed.
Literals are different  types.

1. Array Literal: It is a list of zero or more expressions(elements)

                            Ex: var=[1,2];

2. Boolean Literal:It has two literal value.True or False.

3. Integer Literals:Integers can be expressed in decimal.hexadecimal and binary

                               Ex:var a=42;

4. Floating point literals: fractional part of a number is known as floating point.

                                          Ex: var b=5.1:

5. Object Literal: An object is a list of zero or more pairs of property names values associated with it.

6. RegExp: Literal is a pattern enclosed in slaches.
                    Ex:var re= \ab+c\;
String Literal:Zero or more expressions enclosed in angular braces

EX:
Code:


Output:

Variables:

• Variables are used to store the values.
• variables values can be changed.
• Variables can not be keywords.
• These are case sensitive.
• Syntax: var var-name:value.

EX:
Code:

Output:




Expressions:

• Expressions are units of code that can be evaluated and resolve to a value.
• Any expression is any valid set of literals,variables and expressions that evaluates a single value.
• Syntax: var name=value or value=operand; 

Code:

OUTPUT:

Comments:

• Comments are used to make the program much more easier to undersand.
• Any text between the comments will not be executed.
• In Javascript we have 2 types of comments.
 Single line comment
 Multi line comment

1. Single line comments:

•  These are represented with // comments.
•  These are used for single line of statements.
•  Any code between these slashes will never execute. 

2. Multi line comments:

• These are Represented with /* and */.
• These are used for block of statements or group of statements. 

EX:

Code:

OUTPUT:

JavaScript and Camel case:

• Javascript is case sensitive.
• The first character should not be a number.
• we can use both upper case and lower case letters.

EX: var Num1;

var num1;