The onscroll
property of the GlobalEventHandlers
mixin is an event handler 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.
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}`;
}