The scroll
event fires an element has been scrolled.
Bubbles | No |
---|---|
Cancelable | No |
Interface | Event |
Event handler property | onscroll |
Note: In iOS UIWebViews, scroll
events are not fired while scrolling is taking place; they are only fired after the scrolling has completed. See Bootstrap issue #16202. Safari and WKWebViews are not affected by this bug.
Examples
Scroll event throttling
Since scroll
events can fire at a high rate, the event handler shouldn't execute computationally expensive operations such as DOM modifications. Instead, it is recommended to throttle the event using requestAnimationFrame()
, setTimeout()
, or a CustomEvent
, as follows.
Note, however, that input events and animation frames are fired at about the same rate, and therefore the optimization below is often unnecessary. This example optimizes thescroll
event for requestAnimationFrame
.
// Reference: http://www.html5rocks.com/en/tutorials/speed/animations/ let last_known_scroll_position = 0; let ticking = false; function doSomething(scroll_pos) { // Do something with the scroll position } window.addEventListener('scroll', function(e) { last_known_scroll_position = window.scrollY; if (!ticking) { window.requestAnimationFrame(function() { doSomething(last_known_scroll_position); ticking = false; }); ticking = true; } });
Note: You can find more examples on the resize
event page.
Specifications
Specification | Status |
---|---|
CSS Object Model (CSSOM) View Module | Working Draft |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
scroll event | Chrome Full support Yes | Edge Full support ≤18 | Firefox Full support Yes | IE ? | Opera ? | Safari ? | WebView Android Full support Yes | Chrome Android Full support Yes | Firefox Android Full support Yes | Opera Android ? | Safari iOS ? | Samsung Internet Android Full support Yes |
Legend
- Full support
- Full support
- Compatibility unknown
- Compatibility unknown
See also
- Document:
scroll
event