HTML <optgroup> class Attribute

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

Example

#

Two <optgroup> elements with class attributes.

<style>
  .optgroup { font-size: 20px; }
  .teal { color: teal; }
  .tomato { color: tomato; }
</style>

<select>
  <option value="">-- Select city -- </option>
  <optgroup class="optgroup teal" label="Europe">
    <option value="stockholm">Stockholm</option>
    <option value="barcelona">Barcelona</option>
    <option value="athens">Athens</option>
  </optgroup>
  <optgroup class="optgroup tomato" label="Asia">
    <option value="bangkok">Bangkok</option>
    <option value="manila">Manila</option>
    <option value="jakarta">Jakarta</option>
  </optgroup>
</select>

Using class

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

Multiple classnames are separated by a space.

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

<optgroup class="classnames">

Values

#

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

More Examples

A class attribute styles an <optgroup> element.
Clicking the button toggles a classname that changes the font size.


<style>
  .optgroup-sm {font-size: 16px;color: teal;}
  .optgroup-lg {font-size: 20px;}
</style>

<select>
  <option value="">-- Select city -- </option>
  <optgroup id="myoptgroup" class="optgroup-sm" label="Europe">
    <option value="stockholm">Stockholm</option>
    <option value="barcelona">Barcelona</option>
    <option value="athens">Athens</option>
  </optgroup>
</select>

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

<script>
  let toggle = () => {
    let element = document.getElementById("myoptgroup");
    element.classList.toggle("optgroup-lg");
  }
</script>

Code explanation

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

The class attribute in <optgroup> assigns a single classname.

Repeatedly clicking the button toggles the second class, resizing the <optgroup> font size.

Notice how the <options> inside changes its font size as well.


Browser support

Here is when class support started for each browser:

Chrome
1.0 Sep 2008
Firefox
1.0 Sep 2002
IE/Edge
1.0 Aug 1995
Opera
1.0 Jan 2006
Safari
1.0 Jan 2003

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