JavaScript: getElementsByClassName

getElementsByClassName() returns the elements that have a specified class, so a script can update a group at once.

What you will learn

How to retrieve several elements by class
How to loop through the returned collection
Why the collection can reflect later DOM changes

Minimal example

<p class="status">Waiting</p>
<p class="status">Waiting</p>
<script>
  const statuses = document.getElementsByClassName('status');
  for (const status of statuses) status.textContent = 'Ready';
</script>

The result is an HTMLCollection. It is array-like but is not a full Array, so use an appropriate loop or convert it when you need array methods.

Common mistakes

Check whether the collection contains an element before indexing it.
Be careful when adding or removing the class while iterating because the collection can be live.
Use querySelectorAll when you need more expressive selectors or a static NodeList.