JavaScript Operators

JavaScript Arithmetic Operator Chart

Operator	English	Example
+	Addition	2 + 4
-	Subtraction	6 - 2
*	Multiplication	5 * 3
/	Division	15 / 3
%	Modulus	43 % 10

Modulus % may be a new operation to you, but it's just a special way of saying "finding the remainder". When you perform a division like 15/3 you get 5, exactly. However, if you do 43/10 you get an answer with a decimal, 4.3. 10 goes into 40 four times and then there is a leftover. This leftover is what is returned by the modulus operator. 43 % 10 would equal 3.

JavaScript Operator Example with Variables

Performing operations on variables that contain values is very common and easy to do. Below is a simple script that performs all the basic arithmetic operations.

HTML & JavaScript Code:

<body>
<script type="text/JavaScript">
<!--
var two = 2
var ten = 10
var linebreak = "<br />"

document.write("two plus ten = ")
var result = two + ten
document.write(result)
document.write(linebreak)

document.write("ten * ten = ")
result = ten * ten
document.write(result)
document.write(linebreak)

document.write("ten / two = ")
result = ten / two
document.write(result)
//-->
</script>
</body>

Display:

two plus ten = 12
ten * ten = 100
ten / two = 5

Comparison Operators

Comparisons are used to check the relationship between variables and/or values. A single equal sign sets a value while a double equal sign (==) compares two values. Comparison operators are used inside conditional statements and evaluate to either true or false. We will talk more about conditional statements in the upcoming lessons.

Operator	English	Example	Result
==	Equal To	x == y	false
!=	Not Equal To	x != y	true
<	Less Than	x < y	true
>	Greater Than	x > y	false
<=	Less Than or Equal To	x <= y	true
>=	Greater Than or Equal To	x >= y	false