Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
The DOM DOMMouseScroll event is fired asynchronously when mouse wheel or similar device is operated and the accumulated scroll amount is over 1 line or 1 page since last event. It's represented by the MouseScrollEvent interface. This event was only implemented by Firefox. You should instead use the standard wheel event.
If you want to prevent the default action of mouse wheel events, it's not enough to handle only this event on Gecko because If scroll amount by a native mouse wheel event is less than 1 line (or less than 1 page when the system setting is by page scroll), other mouse wheel events may be fired without this event.
On Gecko 17 (Firefox 17) or later, you need to call preventDefault() of wheel events which must be fired for every native event.
Use the standardized wheel event if available.