December 7, 2021

How to Get Number of Decimal Places in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to get number of decimal places in javascript. In a decimal number, the whole number part and the fractional part are separated by a decimal point. For example, 7.6235 is a decimal number where 7 is the whole number and 6235 is the decimal part. The number of decimal places is 4.

To get the number of decimal places in the decimal number, we can make use of the split() method and the length property. This method and property are only available for strings, so if the value is of number type, then we have to convert it into string type using the toString() method.

In the following example, we have an input field in which we will enter a random decimal number. Upon click of a button, we will get the number of decimal places and display that on the screen. Please have a look over the code example and the steps given below.

HTML & CSS

We have 4 elements in the HTML file (div, input, button, and h1). The div element is just a wrapper for the rest of the elements.
The innerText for the button element is “Get” 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">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="style.css">
  <title>Document</title>
</head>

<body>

  <div class="container">
    <input type="number" placeholder="Enter Number">
    <button>Get</button>
    <h1>Result</h1>
  </div>

  <script src="script.js"></script>
</body>

</html>

.container {        
    text-align: center;
}

button {
  margin-top: 10px;
  padding: 10px 20px;
}

input {
  display: block;  
  margin: 10px auto;
  padding: 10px 20px;
}

input[type=number]::-webkit-inner-spin-button, 
input[type=number]::-webkit-outer-spin-button { 
  -webkit-appearance: none; 
  margin: 0; 
}

Javascript

We have selected the input element, button element, and h1 element using the document.querySelector() method and stored them in input, btnGet, and output variables respectively.
We have attached a click event listener to the button element.
In the event handler function, we are getting the value from the input element using value property and storing that in the num variable. Since it is coming from an input element, it is by default of string type.
We are calling the split() method to split num into two parts and storing the second part in the decimals variable.
We are using the length property to get the number of decimal places and storing that in the result variable.
We are displaying the result in the h1 element using the innerText property.

let input = document.querySelector("input");
let btnGet = document.querySelector("button");
let output = document.querySelector("h1");

btnGet.addEventListener("click", () => {
  let num = input.value;
  let decimals = num.split(".")[1];
  let result = decimals.length;
  output.innerText = result;
});

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