ws: onclose not called if a client disconnects due to network failure

I’ve got the same problem with detecting connections experiencing network errors. I’ve tried setting keepAlive, as pointed here, but close event still fired only 10 s after network got down. Finally, I figured out how to use Websocket ping-pong mechanism:

var WebSocketServer = require('ws').Server,
    wss = new WebSocketServer({ port: 4444 });

var PONG_TIMEOUT = 1500; //client has 1.5s to respond with pong

wss.on('connection', function connection(ws) {
    var lastPongReceived = Date.now();
    ws._socket.on('data', function(data) {
        if (data[0] == 0x8a) { //opcode of pong response
            lastPongReceived = Date.now();
        }
    });

    var x = setInterval(function() {
        if (Date.now() - lastPongReceived > PONG_TIMEOUT) {
            console.log('pong timeout elapsed');
            //...code to run if connection unavailable
            clearInterval(x);
            ws._socket.destroy(); //ws.close() won't raise 'close' event, because close message 
                                   //cannot be delivered to client      
        }
        if (ws.readyState === 1) {
            ws.ping('.', false);
        } 
    }, 1000);

    ws.on('close', function() {
        console.log('connection closed');
    })
});

This is my implementation: https://github.com/urosjarc/websocketRest.js It’s used in production for 1 year +2000 mobile devices connected which are switching connections (wifi, 3G) all the time. We were having many problems with duplicats but now this lib is running 1 year without error. This is the company that use this lib: http://facilityforhotels.com/

A possible way to handle this issue is illustrated here: https://github.com/websockets/ws#how-to-detect-and-close-broken-connections. Closing, feel free to continue discussing on the closed thread.