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JavaScript Operators

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JavaScript Arithmetic Operator Chart

OperatorEnglishExample
+Addition2 + 4
-Subtraction6 - 2
*Multiplication5 * 3
/Division15 / 3
%Modulus43 % 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.
OperatorEnglishExampleResult
==Equal Tox == yfalse
!=Not Equal Tox != ytrue
<Less Thanx < ytrue
>Greater Thanx > yfalse
<=Less Than or Equal Tox <= ytrue
>=Greater Than or Equal Tox >= yfalse
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