Change font-size using JavaScript

In this tutorial we will learn how to Change font-size using JavaScript. JavaScript and HTML codes are give below.


HTML Code is given below.

<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Change Font Size using JavaScript</title>

<p id="text">Change My Font Size</p>
<button onclick="changeSize(1)">+</button>
<button onclick="changeSize(2)">-</button>
<script src="script.js"></script>

JavaScript Code

Take a look at the JavaScript code given below.

function changeSize(x){
var font = window.getComputedStyle(document.getElementById("text")).fontSize; // getting font size
font = font.replace(/\D/g,'');  // removing 'px' from font size
font = Number(font);    // converting string to number to perform addition and subtraction
font = font+1;    
document.getElementById('text').style.fontSize = font + 'px';
font = font-1;    
document.getElementById('text').style.fontSize = font + 'px';

Video Tutorial

Watch video tutorial on How To Change font-size using JavaScript.

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