VirtualMV/JavaScript/Starting/Operators
Introduction
Overview
By the end of this page you will be able to:

Operators
Arithmetic operators
Operator  Description  Example  Result 
+  Addition  var intNum = 2+2;  4 
  Subtraction  var intNum = 52;  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; 
  or  x=6; y=3; (x==5 y==7) returns false 
!  not  x=6; y=4; x != y returns true; 

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>
Example :Click here to run js1_05.
Note that in the example the variables are assigned numbers. If you accept values from a prompt or a text box (from a form) the "numbers" are actually text so need to be converted if you want to do arithmetic operations on them.
References
virtualMV  Superquick wiki guide  Please give me some feedback 
VirtualMV/JavaScript/Starting/Operators. (2021). In WikiEducator/VirtualMV wiki. Retrieved January 27, 2021, from http:https://wikieducator.org/VirtualMV/JavaScript/Starting/Operators (zotero)
