JavaScript Comparison and Logical Operators

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	Comparing	Returns
==	equal to	x == 8	false
		x == 5	true
		x == "5"	true
===	equal value and equal type	x === 5	true
		x === "5"	false
!=	not equal	x != 8	true
!==	not equal value or not equal type	x !== 5	false
		x !== "5"	true
		x !== 8	true
>	greater than	x > 8	false
<	less than	x < 8	true
>=	greater than or equal to	x >= 8	false
<=	less than or equal to	x <= 8	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:

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 (Ternary) Operator

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

Syntax

Example

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If the variable age is a value below 18, the value of the variable voteable will be "Too young", otherwise the value of voteable will be "Old enough".

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Comparing Different Types

Comparing data of different types may give unexpected results.

When comparing a string with a number, JavaScript will convert the string to a number when doing the comparison. An empty string converts to 0. A non-numeric string converts to NaN which is always false.

Case	Value
2 < 12	true
2 < "12"	true
2 < "John"	false
2 > "John"	false
2 == "John"	false
"2" < "12"	false
"2" > "12"	true
"2" == "12"	false

When comparing two strings, "2" will be greater than "12", because (alphabetically) 1 is less than 2.

To secure a proper result, variables should be converted to the proper type before comparison:

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