The WebSocket.extensions read-only property returns the extensions selected by the server. This is currently only the empty string or a list of extensions as negotiated by the connection.


var extensions = aWebSocket.extensions;


A DOMString.


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

Browser compatibility

ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
extensionsChrome Full support YesEdge Full support 12Firefox Full support 8IE ? Opera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android Full support 8Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes


Full support
Full support
Compatibility unknown
Compatibility unknown