JavaScript - Change the font size of button

In this tutorial, we are going to learn about how to change the font size of a button using JavaScript.

Consider, that we have the following button element in our HTML:

<button id="btn">Login</button>

Now, we want to change the above button font size using JavaScript.

Changing the button font size

To change the font size of a button, first we need to access the button element object inside the JavaScript using the document.getElementById() method.

const btn = document.getElementById("btn");

Now, set its style.fontSize property to your desired size (eg: 10px or 20px or 25px, etc).

btn.style.fontSize = "18px";

It changes the font size of a button element to 18px.

Full example:

<button id="btn">Login</button>

JavaScript:

const btn = document.getElementById("btn");

btn.style.fontSize = "18px"; // changes the font size to 18px