Comparison Operators In JavaScript

In programming and coding dynamic web pages comparisons between values of variables become essential.

JavaScript's Comparison Operators

JavaScript has a range of comparison operators to enable any type of comparison between variables.

The comparison is made to decide over a particular action to be taken. To determine the logic between two variables, we make use of JavaScript’s logical operators.

Conditional operators are special operators which assign a value / variable based on the result of the condition.

With the comparison operators, it’s general comparison of equality or difference. We’ll illustrate the types of comparison and logical operators in the following tables.

Equality Operators

Standard Algebraic Operator JavaScript operator Sample JavaScript Condition Meaning of JavaScript Condition
= == X == Y X is equal to Y
!= X != Y X is not equal to Y

Relational Operators

Standard Algebraic Operator JavaScript operator Sample JavaScript Condition Meaning of JavaScript Condition
> >
X > Y
X is greater than Y
< < X < Y X is less than Y
>= X >= Y X is greater than or equal to Y
<= X <= Y X is less than or Equal to Y

Logical Operators

Standard Algebraic Operator JavaScript operator Sample JavaScript Condition Meaning of JavaScript Condition
AND &&
X < 12 && Y > 20
X is less than 12 AND Y is greater than 20
OR || X > 15 || Y > 20
Either X is greater than 15 OR Y is greater than 20
NOT ! !(X < Y)
It is not that X is less than Y

Conditional Operator Syntax

The syntax for the conditional operators is

variable_name = (condition)? value1:value2

If the ‘condition’ is true then, the ‘value1’ is assigned to variable_name otherwise, ‘value2’ is assigned.

Comparison Operator Example

The example below will give you deeper understanding about the working of these operators.

It uses four if statements to display a time-sensitive greeting on a welcome page. The script obtains local time from the user’s computer and converts it to a 12-hour clock format. The script wishes you “Good Morning” in the morning and “Good Evening” in the Evening.

 
<html>
<head>
<title> Using Relational And Logical Operators </title>
<script type=”text/javascript”>
<!--
Var time;
now=new Date(); // Date is a predefined function and new is used to create                                  //an instance of an object. i.e. it tells that now is refers to function //Date.                                  
hour= now.getHours();
if (hour<12)
document.write( “<h1>Good Morning!! </h1>”);
if (hour >=12)
{
hour=hour-12;
if (hour<6 && hour>12) //&& logically compares truth of two values
document.write(“<h1>Good afternoon!!</h1>”);
if(hour>=6)
document.write(“<h1>Good Evening!!<h1>”);
}
time=(hour>6)?”Day”:”Evening”;
Document.write(<h1>time</h1>);

//-->
</script>
</head>
<body> <p> Click refresh to run the script again </p>
</body>
</html>

This ends the tutorial about the relational, logical and conditional operators in JavaScript.

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