Event
The Event
interface represents an event which takes place in the DOM.
An event can be triggered by the user action e.g. clicking the mouse button or tapping keyboard, or generated by APIs to represent the progress of an asynchronous task. It can also be triggered programmatically, such as by calling the HTMLElement.click()
method of an element, or by defining the event, then sending it to a specified target using EventTarget.dispatchEvent()
.
There are many types of events, some of which use other interfaces based on the main Event
interface. Event
itself contains the properties and methods which are common to all events.
Many DOM elements can be set up to accept (or "listen" for) these events, and execute code in response to process (or "handle") them. Event-handlers are usually connected (or "attached") to various HTML elements (such as <button>
, <div>
, <span>
, etc.) using EventTarget.addEventListener()
, and this generally replaces using the old HTML event handler attributes. Further, when properly added, such handlers can also be disconnected if needed using removeEventListener()
.
Note: One element can have several such handlers, even for the exact same event—particularly if separate, independent code modules attach them, each for its own independent purposes. (For example, a webpage with an advertising-module and statistics-module both monitoring video-watching.)
When there are many nested elements, each with its own handler(s), event processing can become very complicated—especially where a parent element receives the very same event as its child elements because "spatially" they overlap so the event technically occurs in both, and the processing order of such events depends on the Event bubbling and capture settings of each handler triggered.
Interfaces based on Event
Below is a list of interfaces which are based on the main Event
interface, with links to their respective documentation in the MDN API reference.
Note that all event interfaces have names which end in "Event".
AnimationEvent
AudioProcessingEvent
DeprecatedBeforeUnloadEvent
BlobEvent
ClipboardEvent
CloseEvent
CompositionEvent
CustomEvent
DeviceMotionEvent
DeviceOrientationEvent
DragEvent
ErrorEvent
FetchEvent
FocusEvent
FontFaceSetLoadEvent
FormDataEvent
GamepadEvent
HashChangeEvent
HIDInputReportEvent
IDBVersionChangeEvent
InputEvent
KeyboardEvent
MediaStreamEvent
DeprecatedMessageEvent
MouseEvent
MutationEvent
DeprecatedOfflineAudioCompletionEvent
PageTransitionEvent
PaymentRequestUpdateEvent
PointerEvent
PopStateEvent
ProgressEvent
RTCDataChannelEvent
RTCPeerConnectionIceEvent
StorageEvent
SubmitEvent
SVGEvent
DeprecatedTimeEvent
TouchEvent
TrackEvent
TransitionEvent
UIEvent
WebGLContextEvent
WheelEvent
Constructor
Event()
-
Creates an
Event
object, returning it to the caller.
Instance properties
Event.bubbles
Read only-
A boolean value indicating whether or not the event bubbles up through the DOM.
Event.cancelable
Read only-
A boolean value indicating whether the event is cancelable.
Event.composed
Read only-
A boolean indicating whether or not the event can bubble across the boundary between the shadow DOM and the regular DOM.
Event.currentTarget
Read only-
A reference to the currently registered target for the event. This is the object to which the event is currently slated to be sent. It's possible this has been changed along the way through retargeting.
Event.defaultPrevented
Read only-
Indicates whether or not the call to
event.preventDefault()
canceled the event. Event.eventPhase
Read only-
Indicates which phase of the event flow is being processed. It is one of the following numbers:
NONE
,CAPTURING_PHASE
,AT_TARGET
,BUBBLING_PHASE
. Event.isTrusted
Read only-
Indicates whether or not the event was initiated by the browser (after a user click, for instance) or by a script (using an event creation method, for example).
Event.target
Read only-
A reference to the object to which the event was originally dispatched.
Event.timeStamp
Read only-
The time at which the event was created (in milliseconds). By specification, this value is time since epoch—but in reality, browsers' definitions vary. In addition, work is underway to change this to be a
DOMHighResTimeStamp
instead. Event.type
Read only-
The case-insensitive name identifying the type of the event.
Legacy and non-standard properties
Event.cancelBubble
Deprecated-
A historical alias to
Event.stopPropagation()
that should be used instead. Setting its value totrue
before returning from an event handler prevents propagation of the event. Event.explicitOriginalTarget
Non-standard Read only-
The explicit original target of the event.
Event.originalTarget
Non-standard Read only-
The original target of the event, before any retargetings.
Event.returnValue
Deprecated-
A historical property still supported in order to ensure existing sites continue to work. Use
Event.preventDefault()
andEvent.defaultPrevented
instead. Event.scoped
Read only Deprecated-
A boolean value indicating whether the given event will bubble across through the shadow root into the standard DOM. Use
composed
instead.
Instance methods
Event.composedPath()
-
Returns the event's path (an array of 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. Event.preventDefault()
-
Cancels the event (if it is cancelable).
Event.stopImmediatePropagation()
-
For this particular event, prevent all other listeners from being called. This includes listeners attached to the same element as well as those attached to elements that will be traversed later (during the capture phase, for instance).
Event.stopPropagation()
-
Stops the propagation of events further along in the DOM.
Deprecated methods
Event.initEvent()
Deprecated-
Initializes the value of an Event created. If the event has already been dispatched, this method does nothing. Use the constructor (
Event()
instead).
Specifications
Specification |
---|
DOM Standard # interface-event |
Browser compatibility
BCD tables only load in the browser
See also
- Types of events available: Event reference
- Comparison of Event Targets (
target
vs.currentTarget
vs.relatedTarget
vs.originalTarget
) - Creating and triggering custom events