ReadonlyAT_ReadonlybubblesReturns true or false depending on how event was initialized. True if event goes through its target's ancestors in reverse tree order, and false otherwise.
ReadonlyBUBBLING_ReadonlycancelableReturns true or false depending on how event was initialized. Its return value does not always carry meaning, but true can indicate that part of the operation during which event was dispatched, can be canceled by invoking the preventDefault() method.
ReadonlyCAPTURING_ReadonlycomposedReturns true or false depending on how event was initialized. True if event invokes listeners past a ShadowRoot node that is the root of its target, and false otherwise.
ReadonlycurrentReturns the object whose event listener's callback is currently being invoked.
ReadonlydataReturns the data of the message.
ReadonlydefaultReturns true if preventDefault() was invoked successfully to indicate cancelation, and false otherwise.
ReadonlyeventReturns the event's phase, which is one of NONE, CAPTURING_PHASE, AT_TARGET, and BUBBLING_PHASE.
ReadonlyisReturns true if event was dispatched by the user agent, and false otherwise.
ReadonlylastReturns the last event ID string, for server-sent events.
ReadonlyNONEReadonlyoriginReturns the origin of the message, for server-sent events and cross-document messaging.
ReadonlyportsReturns the MessagePort array sent with the message, for cross-document messaging and channel messaging.
ReadonlysourceReturns the WindowProxy of the source window, for cross-document messaging, and the MessagePort being attached, in the connect event fired at SharedWorkerGlobalScope objects.
ReadonlysrcReadonlytargetReturns the object to which event is dispatched (its target).
ReadonlytimeReturns the event's timestamp as the number of milliseconds measured relative to the time origin.
ReadonlytypeReturns the type of event, e.g. "click", "hashchange", or "submit".
Optionalbubbles: booleanOptionalcancelable: booleanOptionaldata: anyOptionalorigin: stringOptionallastEventId: stringOptionalsource: null | MessageEventSourceOptionalports: MessagePort[]
扩展的消息事件接口，包含解析后的数据。