# How to Check if Variable is Decimal in Javascript

In this tutorial, you will learn how to check if variable is decimal in javascript. In a decimal number, the whole number part  is separated from the fractional part using a decimal point or dot (.).

There are numerous ways to check if a variable is decimal or not. We are going to use one of the easiest solutions which involve the usage of the modulus (%) and ternary (?) operators. The ternary operator is also known as the conditional operator which acts similar to the if-else statement. The modulus operator returns the remainder of the division after dividing one number with another.

In the following example, we have one global variable and upon click of a button, we will check if the variable is decimal or not and display the result on the screen.  Please have a look over the code example and the steps given below.

HTML & CSS

• We have 3 elements in the HTML file (div, button, and h1). The div element is just a wrapper for the rest of the elements.
• The innerText for the button element is “Check” and for the h1 element, it is “Result”.
• We have done some basic styling using CSS and added the link to our style.css stylesheet inside the head element.
• We have also included our javascript file script.js with a script tag at the bottom.
<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<body>

<div>
<button>Check</button>
<h1>Result</h1>
</div>

<script src="script.js"></script>
</body>
</html>
body {
text-align: center;
}

div {
display: inline-block;
}

button {
display: inline-block;
}

Javascript

• We have selected the button element and h1 element using the document.querySelector() method and stored them in btnCheck and output variables respectively.
• We have a global variable myVar which holds a decimal number as its value.
• We have attached a click event listener to the button element.
• In the event handler function, we are using modulus (%) and ternary (?) operators to verify whether myVar is decimal or not. Depending upon the result of the check, we will assign “Decimal” or “Not Decimal” to the result variable
• We are displaying the result in the h1 element using the innerText property.
let btnCheck = document.querySelector("button");
let output = document.querySelector("h1");

let myVar = 11.5;