JavaScript Comparison and Logical Operators

From http://www.w3schools.com (Copyright Refsnes Data)

# JavaScript Comparison and Logical Operators

Comparison and Logical operators are used to test for true or false.

## Comparison Operators

Comparison operators are used in logical statements to determine equality or difference between variables or values.

Given that x=5, the table below explains the comparison operators:

Operator | Description | Example
--- | --- | ---
== | is equal to | x==8 is false
=== | is exactly equal to (value and type) | x===5 is true x==="5" is false
!= | is not equal | x!=8 is true
> | is greater than | x>8 is false
< | is less than | x<8 is true
>= | is greater than or equal to | x>=8 is false
<= | is less than or equal to | x<=8 is true

## How Can it be Used

Comparison operators can be used in conditional statements to compare values and take action depending on the result:

    if (age<18) document.write("Too young");

You will learn more about the use of conditional statements in the next chapter of this tutorial.

## Logical Operators

Logical operators are used to determine the logic between variables or values.

Given that x=6 and y=3, the table below explains the logical operators:

Operator | Description | Example
--- | --- | ---
&& | and | (x < 10 && y > 1) is true
|| | or | (x==5 || y==5) is false
! | not | !(x==y) is true

## Conditional Operator

JavaScript also contains a conditional operator that assigns a value to a variable based on some condition.

### Syntax

    variablename=(condition)?value1:value2

### Example

    greeting=(visitor=="PRES")?"Dear President ":"Dear ";

If the variable visitor has the value of "PRES", then the variable greeting will be assigned the value "Dear President " else it will be assigned "Dear".

From http://www.w3schools.com (Copyright Refsnes Data)