JavaScript Comparison and Logical Operators

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

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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 x==5 is true
===	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

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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.

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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

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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".