HTML <aside> class Attribute

The class attribute on an <aside> tag assigns one or more classnames to the aside element. Classes are used to style elements. Classnames are defined in a stylesheet or in a local <style> element.

Example

#

A class attribute styling an <aside> element.
The class gives the element its background color.

Art appreciation classes are
available in these cities:
  • Amsterdam
  • London
  • Paris
  • Rome
  • Berlin
  • New York
  • Houston
  • Los Angeles
<style>
  .azure-aside {padding: 20px;background: paleturquoise;border-radius: 10px;}
</style>

<div style="display:flex;align-items:center;">
 <main>
   Art appreciation classes are<br />
   available in these cities: 
   <ul>
     <li>Amsterdam</li>
     <li>London</li>
     <li>Paris</li>
     <li>Rome</li>
     <li>Berlin</li>
     <li>New York</li>
     <li>Houston</li>
     <li>Los Angeles</li>
   </ul>
 </main>
 
 <aside class="azure-aside">
   <i>For the cheapest flights<br />
   please contact our travel<br />
   partner KLM.</i>
 </aside>
</div>

Using class

The class attribute assigns one or more classnames to the <aside> tag.

Multiple classnames are separated by a space.

Classes (i.e. classnames) are used for styling the aside element.

JavaScript uses classes to access one or more elements by classname.

Tip:  class is a global attribute that can be applied to any HTML element.


Syntax

<aside class="classnames">

Values

#

Value Description
classnames One or more space-separated class names.


More Examples

A class attribute styling an <aside> element.
Clicking the button toggles a classname changing the background color.

Art appreciation classes are
available in these cities:
  • Amsterdam
  • London
  • Paris
  • Rome
  • Berlin
  • New York
  • Houston
  • Los Angeles

<style>
  .aside { padding: 20px; border-radius: 10px;}
  .bg-turquoise { background: paleturquoise; }
  .bg-blue { background: lightblue; }
</style>

<div style="display:flex;align-items:center;">

 <main>
   Art appreciation classes are<br />
   available in these cities: 
   <ul>
     <li>Amsterdam</li>
     <li>London</li>
     <li>Paris</li>
     <li>Rome</li>
     <li>Berlin</li>
     <li>New York</li>
     <li>Houston</li>
     <li>Los Angeles</li>
   </ul>
 </main>
 
 <aside id="myaside" class="aside bg-turquoise">
   <i>For the cheapest flights<br />
   please contact our travel<br />
   partner KLM.</i>
 </aside>

</div>

<br/>
<button onclick="toggle();">Toggle class</button>

<script>
  let toggle = () => {
     let element = document.getElementById("myaside");
     element.classList.toggle("bg-blue");
  }
</script>

Code explanation

Three CSS classes are defined in the <style> element.

The class attribute in <aside> assigns two of those classes.

Repeatedly clicking the button toggles another class that changes the background color.


Browser support

Here is when class support started for each browser:

Chrome
6.0 Sep 2010
Firefox
4.0 Mar 2011
IE/Edge
9.0 Mar 2011
Opera
11.1 Mar 2011
Safari
5.0 Jun 2010

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