The WebSocket object provides the API for creating and managing a WebSocket connection to a server, as well as for sending and receiving data on the connection.

To construct a WebSocket, use the WebSocket() constructor.

Constructor

WebSocket(url[, protocols])
Returns a newly created WebSocket object.

Properties

WebSocket.binaryType
The binary data type used by the connection.
WebSocket.bufferedAmount Read only
The number of bytes of queued data.
WebSocket.extensions Read only
The extensions selected by the server.
WebSocket.onclose
An event listener to be called when the connection is closed.
WebSocket.onerror
An event listener to be called when an error occurs.
WebSocket.onmessage
An event listener to be called when a message is received from the server.
WebSocket.onopen
An event listener to be called when the connection is opened.
WebSocket.protocol Read only
The sub-protocol selected by the server.
WebSocket.readyState Read only
The current state of the connection.
WebSocket.url Read only
The absolute URL of the WebSocket.

Methods

WebSocket.close([code[, reason]])
Closes the connection.
WebSocket.send(data)
Enqueues data to be transmitted.

Example

// Create WebSocket connection.
const socket = new WebSocket('ws://localhost:8080');

// Connection opened
socket.addEventListener('open', function (event) {
    socket.send('Hello Server!');
});

// Listen for messages
socket.addEventListener('message', function (event) {
    console.log('Message from server ', event.data);
});

Specifications

Specification Status Comment
HTML Living Standard
The definition of 'WebSocket' in that specification.
Living Standard Initial definition

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support YesEdge Full support YesFirefox Full support 11
Notes
Full support 11
Notes
Notes See bug 695635.
No support 7 — 11
Prefixed Notes
Prefixed Implemented with the vendor prefix: Moz
Notes Message size limited to 16 MB (see bug 711205).
No support 4 — 6
Notes
Notes Message size limited to 16 MB (see bug 711205).
IE ? Opera Full support YesSafari Full support YesWebView Android ? Chrome Android ? Edge Mobile Full support YesFirefox Android Full support 14
Notes
Full support 14
Notes
Notes See bug 695635.
No support 7 — 14
Prefixed Notes
Prefixed Implemented with the vendor prefix: Moz
Notes Message size limited to 16 MB (see bug 711205).
Opera Android ? Safari iOS Full support YesSamsung Internet Android ?
WebSocket() constructorChrome Full support YesEdge ? Firefox Full support 7
Full support 7
No support 4 — 7
Notes
Notes Parameter protocols not supported.
IE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support 7Opera Android ? Safari iOS ? Samsung Internet Android ?
binaryTypeChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
bufferedAmountChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
closeChrome Full support YesEdge ? Firefox Full support 8
Full support 8
No support 4 — 8
Notes
Notes Parameters not supported, see bug 674716.
IE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
extensionsChrome Full support YesEdge ? Firefox Full support 8IE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support 8Opera Android ? Safari iOS ? Samsung Internet Android ?
oncloseChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
onerrorChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
onmessageChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
onopenChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
protocolChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
readyStateChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
sendChrome Full support YesEdge ? Firefox Full support 18
Notes
Full support 18
Notes
Notes See bug 775368.
No support 11 — 18
Notes
Notes Only parameter of type ArrayBuffer and String supported.
No support 8 — 11
Notes
Notes Only parameter of type String supported.
No support 4 — 8
Notes
Notes Only parameter of type String supported. Returns boolean.
IE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?
urlChrome Full support YesEdge ? Firefox Full support YesIE ? Opera Full support YesSafari ? WebView Android ? Chrome Android Full support YesEdge Mobile ? Firefox Android Full support YesOpera Android ? Safari iOS ? Samsung Internet Android ?

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.
Requires a vendor prefix or different name for use.
Requires a vendor prefix or different name for use.

See also