WheelEvent

The WheelEvent interface represents events that occur due to the user moving a mouse wheel or similar input device.

Don't confuse the wheel event with the scroll event:

• A wheel event doesn't necessarily dispatch a scroll event. For example, the element may be unscrollable at all. Zooming actions using the wheel or trackpad also fire wheel events.
• A scroll event isn't necessarily triggered by a wheel event. Elements can also be scrolled by using the keyboard, dragging a scrollbar, or using JavaScript.
• Even when the wheel event does trigger scrolling, the delta* values in the wheel event don't necessarily reflect the content's scrolling direction.

WheelEvent()

Creates a WheelEvent object.

This interface inherits properties from its ancestors, MouseEvent, UIEvent, and Event.

WheelEvent.deltaX Read only

Returns a double representing the horizontal scroll amount.

WheelEvent.deltaY Read only

Returns a double representing the vertical scroll amount.

WheelEvent.deltaZ Read only

Returns a double representing the scroll amount for the z-axis.

WheelEvent.deltaMode Read only

Returns an unsigned long representing the unit of the delta* values' scroll amount. Permitted values are:

Constant	Value	Description
WheelEvent.DOM_DELTA_PIXEL	0x00	The delta* values are specified in pixels.
WheelEvent.DOM_DELTA_LINE	0x01	The delta* values are specified in lines. Each mouse click scrolls a line of content, where the method used to calculate line height is browser dependent.
WheelEvent.DOM_DELTA_PAGE	0x02	The delta* values are specified in pages. Each mouse click scrolls a page of content.

WheelEvent.wheelDelta Read only Deprecated Non-standard

Returns an integer (32-bit) representing the distance in pixels.

WheelEvent.wheelDeltaX Read only Deprecated Non-standard

Returns an integer representing the horizontal scroll amount.

WheelEvent.wheelDeltaY Read only Deprecated Non-standard

Returns an integer representing the vertical scroll amount.

This interface doesn't define any specific methods, but inherits methods from its ancestors, MouseEvent, UIEvent, and Event.

• wheel event
• Interfaces replaced by this one:
  • Gecko's legacy mouse wheel event object: MouseScrollEvent