How to Add Two Decimal Numbers in Javascript
In this tutorial, you will learn how to add two decimal numbers in javascript. Addition of decimal numbers is one of the basic arithmetic operations which every newbie developer should be able to perform without any issue. But it can also be tricky if you are trying to add 2 decimal numbers that are coming from 2 different input fields.
Almost in every programming language, we have an addition operator (+
) to add one number to another and it is also present in javascript. But since the value present in the input field is of string type, we have to convert it into number type using Number()
method and then do the calculation using addition operator (+
).
In the following example, we have 2 input fields in which we will enter 2 random numbers. Upon click of a button, we will perform addition and display the result 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
, andh1
). Thediv
element is just a wrapper for the rest of the elements. - The
innerText
for thebutton
element is“Add”
and for theh1
element, it is“Result”
. - We have done some basic styling using CSS and added the link to our
style.css
stylesheet inside thehead
element. - We have also included our javascript file
script.js
with ascript
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" id="firstInput" placeholder="Enter Number"> <input type="number" id="secondInput" placeholder="Enter Number"> <button>Add</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 both the
input
elements,button
element, andh1
element using thedocument.querySelector()
method and stored them infirstInput
,secondInput
,btnAdd
, andoutput
variables respectively. - We have attached a
click
event listener to thebutton
element. - In the event handler function, we are passing values of both the
input
elements to theNumber()
method and performing the calculation using the addition operator (+
). The result is stored in theresult
variable. - We only want the
result
to be up to 2 decimal places and that is why we are using thetoFixed()
method and passing 2 as a parameter. - We are displaying the
result
in theh1
element using theinnerText
property.
let firstInput = document.querySelector('#firstInput'); let secondInput = document.querySelector('#secondInput'); let btnAdd = document.querySelector('button'); let output = document.querySelector('h1'); btnAdd.addEventListener('click', () =>{ let result = Number(firstInput.value) + Number(secondInput.value); result = result.toFixed(2); output.innerText = result; });