Element: mousewheel event
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 obsolete and non-standard mousewheel
event is fired asynchronously at an Element
to provide updates while a mouse wheel or similar device is operated. The mousewheel
event was never part of any standard, and while it was implemented by several browsers, it was never implemented by Firefox.
Note:
Instead of this obsolete event, use the standard wheel
event.
Syntax
Use the event name in methods like addEventListener()
, or set an event handler property.
addEventListener("mousewheel", (event) => {});
onmousewheel = (event) => {};
Event type
A WheelEvent
. Inherits from MouseEvent
, UIEvent
and Event
.
Event properties
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 thedelta*
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-
Returns an integer (32-bit) representing the distance in pixels.
WheelEvent.wheelDeltaX
Read only Deprecated-
Returns an integer representing the horizontal scroll amount.
WheelEvent.wheelDeltaY
Read only Deprecated-
Returns an integer representing the vertical scroll amount.
The detail property
The value of the detail
property is always zero, except in Opera, which uses detail
similarly to the Firefox-only DOMMouseScroll
event's detail
value, which indicates the scroll distance in terms of lines, with negative values indicating the scrolling movement is either toward the bottom or toward the right, and positive values indicating scrolling to the top or left.
Note:
On macOS, the scroll distance (and therefore the value of detail
) is computed based on the accelerated scroll distance.
On Linux, 2
or -2
is set per native wheel event.
wheelDelta, wheelDeltaX and wheelDeltaY value
The wheelDelta
attribute value is an abstract value which indicates how far the wheel turned. If the wheel has rotated away from the user, it's positive, otherwise negative. This means that the delta value sign is different from DOM Level 3 Event's wheel
. However, the meaning of the amount of these values is not the same between browsers. See following explanation for the detail.
IE and Opera (Presto) only support wheelDelta
attribute and do not support horizontal scroll.
The wheelDeltaX
attribute value indicates the wheelDelta
attribute value along the horizontal axis. When a user operates the device for scrolling to right, the value is negative. Otherwise, i.e., if it's to left, the value is positive.
The wheelDeltaY
attribute value indicates the wheelDelta
attribute value along the vertical axis. The sign of the value is the same as the wheelDelta
attribute value.
Chrome
On Windows, the value is the same as the delta value of WM_MOUSEWHEEL
or WM_MOUSEHWHEEL
. And also, the value isn't changed even if the scroll amount of system settings is page scroll, i.e., the value is the same as IE on Windows.
On Linux, the value is 120
or -120
per native wheel event. This makes the same behavior as IE and Chrome for Windows.
On Mac, the value is complicated. The value is changed if the device that causes the native wheel event supports continuous scroll.
If the device supports continuous scroll (e.g., trackpad of MacBook or mouse wheel which can be turned smoothly), the value is computed from accelerated scroll amount. In this case, the value is the same as Safari.
If the device does not support continuous scroll (typically, old mouse wheel which cannot be turned smoothly), the value is computed from non-accelerated scroll amount (120 per notch). In this case, the value is different from Safari.
This difference makes a serious issue for web application developers. That is, web developers cannot know if mousewheel
event is caused by which device.
Safari
The value is always computed from accelerated scroll amount. This is really different from other browsers except Chrome with continuous scroll supported device.
Opera (Presto)
The value is always the detail
attribute value ✕ 40
.
On Windows, since the detail
attribute value is computed from actual scroll amount, the value is different from other browsers except the scroll amount per notch is 3 lines in system settings or a page.
On Linux, the value is 80
or -80
per native wheel event. This is different from other browsers.
On Mac, the detail
attribute value is computed from accelerated scroll amount of native event. The value is usually much bigger than Safari's or Chrome's value.
Specifications
Not part of any specification.
Browser compatibility
BCD tables only load in the browser
See also
- The standard
wheel
event to listen to instead.