GlobalEventHandlers.onscroll - Web APIs 编辑

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.

Note: Don't confuse onscroll with onwheel!

onwheel handles general wheel rotation, while onscroll handles scrolling of an object's content.

Syntax

target.onscroll = functionRef

Value

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.

Example

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

HTML

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

CSS

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

JavaScript

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

textarea.onscroll = logScroll;

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

Result

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Document: scroll event
• Element: scroll event