GlobalEventHandlers.onscroll

The onscroll property of the GlobalEventHandlers mixin is an EventHandler that processes scroll events.

The scroll event fires when the document view or an element has been scrolled, whether by the user, a Web API, or the user agent.

target.onscroll = functionRef

functionRef

A function name, or a function expression. The function receives a UIEvent object as its sole argument.

Only one onscroll handler can be assigned to an object at a time.

For greater flexibility, you can pass a scroll event to the EventTarget.addEventListener() method instead.

This example monitors scrolling on a <textarea>, and logs the element's vertical scroll position accordingly.

<textarea>1 2 3 4 5 6 7 8 9</textarea>
<p id="log"></p>

textarea {
  width: 4rem;
  height: 8rem;
  font-size: 3rem;
}

const textarea = document.querySelector('textarea');
const log = document.getElementById('log');

textarea.onscroll = logScroll;

function logScroll(e) {
  log.textContent = `Scroll position: ${e.target.scrollTop}`;
}

• Document: scroll event
• Element: scroll event