Capturing Scroll Wheel Events

Question

I want to capture an event when a user scrolls their scroll wheel in a situation where the page does not scroll/is not scrollable. However, the standard JS scroll event only fires when the browser actually does scroll, and will not fire for a DOM element styled to have overflow hidden.

Google maps' scroll to zoom is an example of the type of behavior I'm looking for.

Does anyone have any idea how to accomplish something like this?

Thanks.

Answer 1

You can capture the mouse-wheel event just fine:

$( '#yourElement' ).on( 'DOMMouseScroll mousewheel', function () {
    ...
});

Live demo: http://jsfiddle.net/chtNP/1/

(I'm using jQuery to bind the event handler, but it works regardless of which API you use, of course.)

Answer 2

At this time, Firefox define DOMMouseScroll and wheel events. Chrome, Opera and IE (latest, again!) define mousewheel.

This is how I did it:

if(window.onwheel !== undefined) {
    window.addEventListener('wheel', onMouseWheel)
} else if(window.onmousewheel !== undefined) {
    window.addEventListener('mousewheel', onMouseWheel)
} else {
    // unsupported browser
}

Note that addEventListener support in older IE versions needs a polyfill. Alternatively you can use the old window.mousewheel = function(){} or whatever method.

As you can see, the event listener is attached to the window object. You can't attach it to elements, in a cross-browser fashion. You can use the event object target property to see where it was triggered, and do a filter on that basis.

PS: One more cross-browser consideration: In IE, you have to use the "wheelDelta" property (and invert it's sign!) inside the event object when processing it in the callback function ("onMouseWheel"). Other browsers will populate "deltaY" (or "deltaX" for horizontal scrolling).