Event class Null safety

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 interface. 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.

Implementers
Annotations

Constructors

Event(String type, [EventInit? eventInitDict])
factory

Properties

bubbles bool
A boolean indicating whether or not the event bubbles up through the DOM.
read-only
cancelable bool
A boolean indicating whether the event is cancelable.
read-only
cancelBubble bool
A historical alias to Event.stopPropagation(). Setting its value to true before returning from an event handler prevents propagation of the event.
read / write
composed bool
A boolean indicating whether or not the event can bubble across the boundary between the shadow DOM and the regular DOM.
read-only
currentTarget EventTarget?
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.
read-only
defaultPrevented bool
Indicates whether or not the call to event.preventDefault() canceled the event.
read-only
eventPhase int
Indicates which phase of the event flow is being processed.
read-only
hashCode int
The hash code for this object. [...]
read-only, inherited
isTrusted bool
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, like Event.initEvent).
read-only
returnValue ↔ dynamic
A historical property introduced by Internet Explorer and eventually adopted into the DOM specification in order to ensure existing sites continue to work. Ideally, you should try to use Event.preventDefault() and Event.defaultPrevented instead, but you can use if you choose to do so.
covariant, read / write
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited
srcElement EventTarget?
A non-standard alias (from old versions of Microsoft Internet Explorer) for Event.target. Some other browsers are starting to support it for web compatibility purposes.
read-only
target EventTarget?
A reference to the target to which the event was originally dispatched.
read-only
timeStamp double
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.
read-only
type String
The name of the event. Case-insensitive.
read-only

Methods

composedPath() Iterable<EventTarget>
Returns the event’s path (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. var composed = Event.composedPath();
initEvent(String type, [bool? bubbles = false, bool? cancelable = false]) Object
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
inherited
preventDefault() Object
Cancels the event (if it is cancelable). event.preventDefault();
stopImmediatePropagation() Object
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.stopImmediatePropagation();
stopPropagation() Object
Stops the propagation of events further along in the DOM. event.stopPropagation();
toString() String
A string representation of this object. [...]
inherited

Operators

operator ==(Object other) bool
The equality operator. [...]
inherited

Static Properties

AT_TARGET int
read-only
BUBBLING_PHASE int
read-only
CAPTURING_PHASE int
read-only
NONE int
read-only