JavaScript Operators
Operators in JavaScript are very similar to operators that appear in other programming languages. The definition of an operator is a symbol that is used to perform an operation. Most often these operations are arithmetic (addition, subtraction, etc), but not always.
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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:
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 |
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