HTML Standard
Communication
9.1
The
MessageEvent
interface
Communication
The
WebSocket
interface used
to be defined here. It is now defined in
WebSockets
[WEBSOCKETS]
9.1
The
MessageEvent
interface
MessageEvent
Support in all current engines.
Firefox
3+
Safari
4+
Chrome
2+
Opera
10.6+
Edge
79+
Edge (Legacy)
12+
Internet Explorer
9+
Firefox Android
Safari iOS
Chrome Android
WebView Android
37+
Samsung Internet
Opera Android
11+
Messages in
server-sent events
cross-document messaging
channel messaging
broadcast channels
, and
WebSockets
use
the
MessageEvent
interface for their
message
events:
[WEBSOCKETS]
Exposed
=(
Window
Worker
AudioWorklet
)]
interface
MessageEvent
Event
constructor
DOMString
type
optional
MessageEventInit
eventInitDict
= {});
readonly
attribute
any
data
readonly
attribute
USVString
origin
readonly
attribute
DOMString
lastEventId
readonly
attribute
MessageEventSource
source
readonly
attribute
FrozenArray
MessagePort
ports
undefined
initMessageEvent
DOMString
type
optional
boolean
bubbles
false
optional
boolean
cancelable
false
optional
any
data
null
optional
USVString
origin
= "",
optional
DOMString
lastEventId
= "",
optional
MessageEventSource
source
null
optional
sequence
MessagePort
ports
= []);
};
dictionary
MessageEventInit
EventInit
any
data
null
USVString
origin
= "";
DOMString
lastEventId
= "";
MessageEventSource
source
null
sequence
MessagePort
ports
= [];
};
typedef
WindowProxy
or
MessagePort
or
ServiceWorker
MessageEventSource
Each
MessageEvent
has an
origin
(an
origin
, a string, or null), initially
null.
event
data
MessageEvent/data
Support in all current engines.
Firefox
3+
Safari
4+
Chrome
2+
Opera
12.1+
Edge
79+
Edge (Legacy)
12+
Internet Explorer
9+
Firefox Android
Safari iOS
Chrome Android
WebView Android
37+
Samsung Internet
Opera Android
12.1+
Returns the data of the message.
event
origin
MessageEvent/origin
Support in all current engines.
Firefox
3+
Safari
4+
Chrome
2+
Opera
12.1+
Edge
79+
Edge (Legacy)
12+
Internet Explorer
9+
Firefox Android
Safari iOS
Chrome Android
WebView Android
37+
Samsung Internet
Opera Android
12.1+
Returns the origin of the message, for
server-sent events
and
cross-document messaging
event
lastEventId
MessageEvent/lastEventId
Support in all current engines.
Firefox
3+
Safari
4+
Chrome
2+
Opera
12.1+
Edge
79+
Edge (Legacy)
17+
Internet Explorer
9+
Firefox Android
Safari iOS
Chrome Android
WebView Android
37+
Samsung Internet
Opera Android
12.1+
Returns the
last event ID string
for
server-sent events
event
source
MessageEvent/source
Support in all current engines.
Firefox
3+
Safari
4+
Chrome
2+
Opera
12.1+
Edge
79+
Edge (Legacy)
12+
Internet Explorer
No
Firefox Android
Safari iOS
Chrome Android
WebView Android
37+
Samsung Internet
Opera Android
12.1+
Returns the
WindowProxy
of the source window, for
cross-document
messaging
, and the
MessagePort
being attached, in the
connect
event fired at
SharedWorkerGlobalScope
objects.
event
ports
MessageEvent/ports
Support in all current engines.
Firefox
3+
Safari
4+
Chrome
4+
Opera
12.1+
Edge
79+
Edge (Legacy)
12+
Internet Explorer
9+
Firefox Android
Safari iOS
Chrome Android
WebView Android
37+
Samsung Internet
Opera Android
12.1+
Returns the
MessagePort
array sent with the message, for
cross-document
messaging
and
channel messaging
The
data
attribute must return the value it was initialized to. It represents the message being sent.
The
origin
attribute represents, in
server-sent
events
and
cross-document messaging
, the
origin
of the document that sent the message (typically
the scheme, hostname, and port of the document, but not its path or
fragment
).
The
origin
getter steps are:
If
this
's
origin
is
an
origin
, then return the
serialization
of
this
's
origin
If
this
's
origin
is
null, then return the empty string.
Return
this
's
origin
When the
origin
attribute is "initialized"
(during
MessageEvent
's
constructor
, for
example), the initialization value is placed into the object's
origin
Objects implementing the
MessageEvent
interface's
extract an origin
steps are to return
this
's
origin
if it is an
origin
; otherwise null.
The
lastEventId
attribute must return the value it
was initialized to. It represents, in
server-sent events
, the
last event ID string
of the event source.
The
source
attribute must return the value it was
initialized to. It represents, in
cross-document messaging
, the
WindowProxy
of the
browsing context
of the
Window
object
from which the message came; and in the
connect
events used by
shared workers
, the newly connecting
MessagePort
The
ports
attribute must return the value it was initialized to. It represents, in
cross-document
messaging
and
channel messaging
, the
MessagePort
array being
sent.
The
initMessageEvent(
type
bubbles
cancelable
data
origin
lastEventId
source
ports
method must initialize the event in a manner
analogous to the similarly-named
initEvent()
method.
[DOM]
Various APIs (e.g.,
WebSocket
EventSource
) use the
MessageEvent
interface for their
message
event
without using the
MessagePort
API.