How to Trim Decimals in Javascript

In this tutorial, you will learn how to trim decimals in javascript. There are times when we only care about the whole number and not the decimal part of the number, even if the decimal representation of the number provides an exact value. From a developer perspective, it can be a bit tricky to trim decimals from a number.

There are numerous ways to trim decimals from a number. We are going to use the simplest approach which involves the usage of the Math object. This object contains trunc() method which removes the decimal part and returns the integer part of a number.

In the following example, we have one global variable that holds a decimal number. Upon click of a button, we will trim decimals from the number and display the result on the screen.  Please have a look over the code example and the steps given below.


  • We have 3 elements in the HTML file (divbutton, and h1). The div element is just a wrapper for the rest of the elements.
  • The innerText for the button element is “Remove”.
  • 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">
  <link rel="stylesheet" href="style.css">


  <div class="container">    

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

.container {        
    text-align: center;

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


  • We have selected the button element and h1 element using the document.querySelector() method and stored them in btnRemove and output variables respectively.
  • We have attached a click event listener to the button element.
  • We have a global variable myNum which holds a decimal number as its value.
  • We are displaying the original number in the h1 element using the innerText property.
  • In the event handler function, we are calling trunc() method of Math object and passing myNum as a parameter. As a result, it will trim decimals from the number and will return the integer part.
  • The returned value is stored in the result variable.
  • We are displaying the result in the h1 element using the innerText property.
let btnRemove = document.querySelector("button");
let output = document.querySelector("h1");

let myNum= 1214.101200;

output.innerText = myNum;

btnRemove.addEventListener("click", () => {
  let result = Math.trunc(myNum);
  output.innerText = result;