WheelEvent extension type

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

Note: This is the standard wheel event interface to use. Old versions of browsers implemented the non-standard and non-cross-browser-compatible MouseWheelEvent and MouseScrollEvent interfaces. Use this interface and avoid the non-standard ones.

Don't confuse the wheel event with the Element.scroll_event 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.

API documentation sourced from MDN Web Docs.

on

JSObject

Implemented types

Available extensions

Constructors

WheelEvent(String type, [WheelEventInit eventInitDict]): factory

Properties

altKey → bool: The MouseEvent.altKey read-only property is a boolean value that indicates whether the alt key was pressed or not when a given mouse event occurs.
no setterinherited
bubbles → bool: The bubbles read-only property of the Event interface indicates whether the event bubbles up through the DOM tree or not.
no setterinherited
button → int: The MouseEvent.button read-only property indicates which button was pressed on the mouse to trigger the event.
no setterinherited
buttons → int: The MouseEvent.buttons read-only property indicates which buttons are pressed on the mouse (or other input device) when a mouse event is triggered.
no setterinherited
cancelable → bool: The cancelable read-only property of the Event interface indicates whether the event can be canceled, and therefore prevented as if the event never happened.
no setterinherited
cancelBubble ↔ bool: The cancelBubble property of the Event interface is deprecated. Use Event.stopPropagation instead. Setting its value to true before returning from an event handler prevents propagation of the event. In later implementations, setting this to false does nothing. See Browser compatibility for details.
getter/setter pairinherited
client → Point<num>: Available on MouseEvent, provided by the EventGlue extension
A Point representation of the clientX and clientY properties of this MouseEvent.
no setter
clientX → int: The clientX read-only property of the MouseEvent interface provides the horizontal coordinate within the application's at which the event occurred (as opposed to the coordinate within the page).
no setterinherited
clientY → int: The clientY read-only property of the MouseEvent interface provides the vertical coordinate within the application's at which the event occurred (as opposed to the coordinate within the page).
no setterinherited
composed → bool: The read-only composed property of the Event interface returns a boolean value which indicates whether or not the event will propagate across the shadow DOM boundary into the standard DOM.
no setterinherited
ctrlKey → bool: The MouseEvent.ctrlKey read-only property is a boolean value that indicates whether the ctrl key was pressed or not when a given mouse event occurs.
no setterinherited
currentTarget → EventTarget?: The currentTarget read-only property of the Event interface identifies the element to which the event handler has been attached.
no setterinherited
defaultPrevented → bool: The defaultPrevented read-only property of the Event interface returns a boolean value indicating whether or not the call to Event.preventDefault canceled the event.
no setterinherited
deltaMode → int: The WheelEvent.deltaMode read-only property returns an unsigned long representing the unit of the delta values scroll amount. Permitted values are:
no setter
deltaX → double: The WheelEvent.deltaX read-only property is a double representing the horizontal scroll amount in the WheelEvent.deltaMode unit.
no setter
deltaY → double: The WheelEvent.deltaY read-only property is a double representing the vertical scroll amount in the WheelEvent.deltaMode unit.
no setter
deltaZ → double: The WheelEvent.deltaZ read-only property is a double representing the scroll amount along the z-axis, in the WheelEvent.deltaMode unit.
no setter
detail → int: The UIEvent.detail read-only property, when non-zero, provides the current (or next, depending on the event) click count.
no setterinherited
eventPhase → int: The eventPhase read-only property of the Event interface indicates which phase of the event flow is currently being evaluated.
no setterinherited
hashCode → int: The hash code for this object.
no setterinherited
isDefinedAndNotNull → bool: Available on JSAny?, provided by the NullableUndefineableJSAnyExtension extension

no setter
isNull → bool: Available on JSAny?, provided by the NullableUndefineableJSAnyExtension extension
Whether this value corresponds to JavaScript null.
no setter
isTrusted → bool: The isTrusted read-only property of the Event interface is a boolean value that is true when the event was generated by the user agent (including via user actions and programmatic methods such as HTMLElement.focus), and false when the event was dispatched via EventTarget.dispatchEvent. The only exception is the click event, which initializes the isTrusted property to false in user agents.
no setterinherited
isTruthy → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of !!this in JavaScript.
no setter
isUndefined → bool: Available on JSAny?, provided by the NullableUndefineableJSAnyExtension extension
Whether this value corresponds to JavaScript undefined.
no setter
isUndefinedOrNull → bool: Available on JSAny?, provided by the NullableUndefineableJSAnyExtension extension

no setter
metaKey → bool: The MouseEvent.metaKey read-only property is a boolean value that indicates whether the meta key was pressed or not when a given mouse event occurs.
no setterinherited
movementX → double: The movementX read-only property of the MouseEvent interface provides the difference in the X coordinate of the mouse pointer between the given event and the previous Element.mousemove_event event. In other words, the value of the property is computed like this: currentEvent.movementX = currentEvent.screenX - previousEvent.screenX.
no setterinherited
movementY → double: The movementY read-only property of the MouseEvent interface provides the difference in the Y coordinate of the mouse pointer between the given event and the previous Element.mousemove_event event. In other words, the value of the property is computed like this: currentEvent.movementY = currentEvent.screenY - previousEvent.screenY.
no setterinherited
not → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of !this in JavaScript.
no setter
offsetX → double: The offsetX read-only property of the MouseEvent interface provides the offset in the X coordinate of the mouse pointer between that event and the padding edge of the target node.
no setterinherited
offsetY → double: The offsetY read-only property of the MouseEvent interface provides the offset in the Y coordinate of the mouse pointer between that event and the padding edge of the target node.
no setterinherited
pageX → double: The pageX read-only property of the MouseEvent interface returns the X (horizontal) coordinate (in pixels) at which the mouse was clicked, relative to the left edge of the entire document. This includes any portion of the document not currently visible.
no setterinherited
pageY → double: The pageY read-only property of the MouseEvent interface returns the Y (vertical) coordinate (in pixels) at which the mouse was clicked, relative to the top edge of the entire document. This includes any portion of the document not currently visible.
no setterinherited
relatedTarget → EventTarget?: The MouseEvent.relatedTarget read-only property is the secondary target for the mouse event, if there is one.
no setterinherited
returnValue ↔ bool: The Event property returnValue indicates whether the default action for this event has been prevented or not.
getter/setter pairinherited
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
screenX → int: The screenX read-only property of the MouseEvent interface provides the horizontal coordinate (offset) of the mouse pointer in screen coordinates.
no setterinherited
screenY → int: The screenY read-only property of the MouseEvent interface provides the vertical coordinate (offset) of the mouse pointer in screen coordinates.
no setterinherited
shiftKey → bool: The MouseEvent.shiftKey read-only property is a boolean value that indicates whether the shift key was pressed or not when a given mouse event occurs.
no setterinherited
srcElement → EventTarget?: The deprecated Event.srcElement is an alias for the Event.target property. Use Event.target instead.
no setterinherited
target → EventTarget?: The read-only target property of the Event interface is a reference to the object onto which the event was dispatched. It is different from Event.currentTarget when the event handler is called during the bubbling or capturing phase of the event.
no setterinherited
timeStamp → double: The timeStamp read-only property of the Event interface returns the time (in milliseconds) at which the event was created.
no setterinherited
type → String: The type read-only property of the Event interface returns a string containing the event's type. It is set when the event is constructed and is the name commonly used to refer to the specific event, such as click, load, or error.
no setterinherited
view → Window?: The UIEvent.view read-only property returns the object from which the event was generated. In browsers, this is the Window object the event happened in.
no setterinherited
which → int: The UIEvent.which read-only property of the UIEvent interface returns a number that indicates which button was pressed on the mouse, or the numeric keyCode or the character code (charCode) of the key pressed on the keyboard.
no setterinherited
x → double: The MouseEvent.x property is an alias for the MouseEvent.clientX property.
no setterinherited
y → double: The MouseEvent.y property is an alias for the MouseEvent.clientY property.
no setterinherited

Methods

add(JSAny? any) → JSAny: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this + any in JavaScript.
and(JSAny? any) → JSAny?: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this && any in JavaScript.
callMethod<R extends JSAny?>(JSAny method, [JSAny? arg1, JSAny? arg2, JSAny? arg3, JSAny? arg4]) → R: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Calls method on this JSObject with up to four arguments.
callMethodVarArgs<R extends JSAny?>(JSAny method, [List<JSAny?>? arguments]) → R: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Calls method on this JSObject with a variable number of arguments.
composedPath() → JSArray<EventTarget>: The composedPath() method of the Event interface returns the event's path which is an array of the objects on which listeners will be invoked. This does not include nodes in shadow trees if the shadow root was created with its ShadowRoot.mode closed.
inherited
dartify() → Object?: Available on JSAny?, provided by the JSAnyUtilityExtension extension
Converts a JavaScript JSON-like value to the Dart equivalent if possible.
delete(JSAny property) → JSBoolean: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Deletes the property with key property from this JSObject.
divide(JSAny? any) → JSAny: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this / any in JavaScript.
equals(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this == any in JavaScript.
exponentiate(JSAny? any) → JSAny: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this ** any in JavaScript.
getModifierState(String keyArg) → bool: The MouseEvent.getModifierState() method returns the current state of the specified modifier key: true if the modifier is active (i.e., the modifier key is pressed or locked), otherwise, false.
inherited
getProperty<R extends JSAny?>(JSAny property) → R: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
The value of the property key property of this JSObject.
greaterThan(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this > any in JavaScript.
greaterThanOrEqualTo(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this >= any in JavaScript.
has(String property) → bool: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Shorthand helper for hasProperty to check whether this JSObject contains the property key property, but takes and returns a Dart value.
hasProperty(JSAny property) → JSBoolean: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Whether or not this JSObject contains the property key property.
initEvent(String type, [bool bubbles, bool cancelable]) → void: The Event.initEvent() method is used to initialize the value of an event created using Document.createEvent.
inherited
initMouseEvent(String typeArg, [bool bubblesArg, bool cancelableArg, Window? viewArg, int detailArg, int screenXArg, int screenYArg, int clientXArg, int clientYArg, bool ctrlKeyArg, bool altKeyArg, bool shiftKeyArg, bool metaKeyArg, int buttonArg, EventTarget? relatedTargetArg]) → void: The MouseEvent.initMouseEvent() method initializes the value of a mouse event once it's been created (normally using the Document.createEvent method).
inherited
initUIEvent(String typeArg, [bool bubblesArg, bool cancelableArg, Window? viewArg, int detailArg]) → void: The UIEvent.initUIEvent() method initializes a UI event once it's been created.
inherited
instanceof(JSFunction constructor) → bool: Available on JSAny?, provided by the JSAnyUtilityExtension extension
Whether this JSAny? is an instanceof constructor.
instanceOfString(String constructorName) → bool: Available on JSAny?, provided by the JSAnyUtilityExtension extension
Whether this JSAny? is an instanceof the constructor that is defined by constructorName, which is looked up in the globalContext.
isA<T extends JSAny?>() → bool: Available on JSAny?, provided by the JSAnyUtilityExtension extension
Whether this JSAny? is an instance of the JavaScript type that is declared by T.
lessThan(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this < any in JavaScript.
lessThanOrEqualTo(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this <= any in JavaScript.
modulo(JSAny? any) → JSAny: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this % any in JavaScript.
multiply(JSAny? any) → JSAny: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this * any in JavaScript.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
notEquals(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this != any in JavaScript.
or(JSAny? any) → JSAny?: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this || any in JavaScript.
preventDefault() → void: The preventDefault() method of the Event interface tells the that if the event does not get explicitly handled, its default action should not be taken as it normally would be.
inherited
setProperty(JSAny property, JSAny? value) → void: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Write the value of property key property of this JSObject.
stopImmediatePropagation() → void: The stopImmediatePropagation() method of the Event interface prevents other listeners of the same event from being called.
inherited
stopPropagation() → void: The stopPropagation() method of the Event interface prevents further propagation of the current event in the capturing and bubbling phases. It does not, however, prevent any default behaviors from occurring; for instance, clicks on links are still processed. If you want to stop those behaviors, see the Event.preventDefault method. It also does not prevent propagation to other event-handlers of the current element. If you want to stop those, see Event.stopImmediatePropagation.
inherited
strictEquals(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this === any in JavaScript.
strictNotEquals(JSAny? any) → JSBoolean: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this !== any in JavaScript.
subtract(JSAny? any) → JSAny: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this - any in JavaScript.
toString() → String: A string representation of this object.
inherited
typeofEquals(String typeString) → bool: Available on JSAny?, provided by the JSAnyUtilityExtension extension
Whether the result of typeof on this JSAny? is typeString.
unsignedRightShift(JSAny? any) → JSNumber: Available on JSAny?, provided by the JSAnyOperatorExtension extension
The result of this >>> any in JavaScript.

Operators

operator ==(Object other) → bool: The equality operator.
inherited
operator [](String property) → JSAny?: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Shorthand helper for getProperty to get the value of the property key property of this JSObject, but takes a Dart value.
operator []=(String property, JSAny? value) → void: Available on JSObject, provided by the JSObjectUnsafeUtilExtension extension
Shorthand helper for setProperty to write the value of the property key property of this JSObject, but takes a Dart value.

Constants

DOM_DELTA_LINE → const int
DOM_DELTA_PAGE → const int
DOM_DELTA_PIXEL → const int