WebSocket: message event
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Note: This feature is available in Web Workers.
The message
event is fired when data is received through a WebSocket
.
Syntax
Use the event name in methods like addEventListener()
, or set an event handler property.
addEventListener("message", (event) => {});
onmessage = (event) => {};
Event type
A MessageEvent
. Inherits from Event
.
Event properties
In addition to the properties listed below, properties from the parent interface, Event
, are available.
data
Read only-
The data sent by the message emitter. The type of this property depends on the type of the WebSocket message and the value of
WebSocket.binaryType
.- If the message type is "text", then this field is a string.
- If the message type is "binary" type, then the type of this property can be inferred from the
binaryType
of this socket:ArrayBuffer
ifbinaryType
is"arraybuffer"
,Blob
ifbinaryType
is"blob"
. This does not have an associated media type (Blob.type
is""
).
origin
Read only-
A string representing the origin of the message emitter.
Other properties from the MessageEvent
interface are present, but do not pertain to the WebSocket API and are left at their default values:
lastEventId
Read onlysource
Read onlyports
Read only
Examples
// Create WebSocket connection.
const socket = new WebSocket("ws://localhost:8080");
// Listen for messages
socket.addEventListener("message", (event) => {
console.log("Message from server ", event.data);
});
Specifications
Specification |
---|
WebSockets Standard # dom-websocket-onmessage |
Browser compatibility
BCD tables only load in the browser