MessageEvent
interface
Messages
in
server-sent
events
,
Web
sockets
,
cross-document
messaging
,
channel
messaging
,
and
broadcast
channels
use
the
MessageEvent
interface
for
their
message
events:
[Constructor(DOMString type, optional MessageEventInit eventInitDict), Exposed=(Window,Worker,AudioWorklet)]
interface MessageEvent : Event {
readonly attribute any data;
readonly attribute USVString origin;
readonly attribute DOMString lastEventId;
readonly attribute MessageEventSource? source;
readonly attribute FrozenArray<MessagePort> ports;
void 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
;
data
Returns the data of the message.
origin
Returns the origin of the message, for server-sent events and cross-document messaging .
lastEventId
Returns the last event ID string , for server-sent events .
source
Returns
the
WindowProxy
of
the
source
window,
for
cross-document
messaging
,
and
the
MessagePort
being
attached,
in
the
connect
event
fired
at
SharedWorkerGlobalScope
objects.
ports
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
must
return
the
value
it
was
initialized
to.
It
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
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()
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.