# VirtualMV/JavaScript/Starting/Operators

## Introduction

### Overview By the end of this page you will be able to: Describe common operators in JavaScript

## Operators

### Arithmetic operators

 Operator Description Example Result + Addition var intNum = 2+2; 4 - Subtraction var intNum = 5-2; 3 * Multiplication var intNum = 4*5; 20 / Division var intNum=15/5; var 3 % Modulus (remainder after division) var intNum = 5%2; var intNum = 10%8; 1 2 ++ Increment var intX=5; intX++; intX=6 -- Decrement intX=3; intX--; intX=2

### Comparison Operators

 Operator Description Example == is equal to 4==8 returns false != is not equal 4!=8 returns true > is greater than 4>8 returns false < is less than 4<8 returns true >= is greater than or equal to 4>=8 returns false <= is less than or equal to 4<=8 returns true

### Logical Operators

 Operator Description Example && and x=5;y=4;(x<10 &&y>1) returns true || or x=6;y=3;(x==5|| y==7) returns false ! not x=6;y=4;x != y returns true;

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3 logicians walk into a cafe. The waiter asks "do you ALL want a drink?"

The first says "I don't know", the second says "I don't know" the third says "Yes please"

### Conditional Operators

JavaScript also contains a conditional operator that assigns a value to a variable based on some condition. JavaScript Comparison and Logical Operators (W3Schools)

#### Examples

The following code shows that JavaScript allows for some quite sophisticated assignments.

//This allows you to change a greeting based on the contents of the txtVisitor variable
//if the visitor = PRES then put Dear President otherwise just Dear

var txtGreeting=(txtVisitor=="PRES")?"Dear President ":"Dear ";

// Here a date object is created.
// If d is < 10 then a zero is added to the front else just leave d as is.
var date = new Date();
var d  = date.getDate();
var day = (parseInt(d) < 10) ? '0' + d : d;

### Example (js1_05)

<html>
<body>
<script type="text/javascript">
var intA = 3;
var intB = 5;
var intSum = intA + intB;
var intProd = intA * intB;
document.write("The sum of 3 and 5 is " + intSum +"<br />");
document.write("The product of 3 and 5 is " + intProd);
</script>
<p>This example declares some variables, assigns values to them,
performs a calculation and then displays the results.</p>
</body>
</html>