What is the best way to detect websocket support using Javascript?

Question

I\'m trying to use Javascript to detect if a web browser supports websockets, but using only feature-based detection, I\'m getting false positives, so I added a user agent t

Answer 1

None of the above answers by itself was sufficient in my tests. The following code seems to be working fine:

    function nll( o ) { return CS.undefined === typeof o || null === o; }
    // ...
    function check_ws_object() {
        try {
            var websocket = new WebSocket( "wss://echo.websocket.org" );
            return true;
        } catch ( e ) { ; }
        return false;
    }
    //
    function check_support() {
        if ( !( WebSocket in window ) ) {
            if ( nll( window.WebSocket) ) {
                if ( !this.check_ws_object() ) {
                    alert( "This browser doesn't support HTML5 Web Sockets!" );
                    return false;
                }
            }
        }
        return true;
    },

The above tests are sorted, so that the faster ones come first.

Answer 2

after reading @gzost's response.. I started tinkering.. since nothing else can properly detect WS's on my android phone... even websocket.org says i have it, but then fails to connect.

Anyways, try this workaround.. seems to properly detect it on/off with chrome, FF, safari and the default android browser.

var has_ws=0;
function checkWebSocket(){
  try{
    websocket = new WebSocket("ws:websocket.org");
    websocket.close('');
  }catch(e){ //throws code 15 if has socket to me babies
    has_ws=1;
  }
}

$(document).ready(function(){
  checkWebSocket();
});

Answer 3

I think the Modernizr library is what you are looking for: http://modernizr.com/

Once you include the library on your page, you can use a simple check like:

if(Modernizr.websockets){
    // socket to me baby
}

Answer 4

This page comes on top in google search.

In year 2016 cutting the mustard for modern WebSockets implementation (no prefixes such as MozWebSocket) would be

if (
  'WebSocket' in window && window.WebSocket.CLOSING === 2
) {
 // supported
}

http://www.w3.org/TR/websockets/#the-websocket-interface

Answer 5

This is the shortest solution and is used by Modernizr. Simply add this to your code

supportsWebSockets = 'WebSocket' in window || 'MozWebSocket' in window;

then you can use it by running

if (supportsWebSockets) {
     // run web socket code
}