Failed connections of WebSocket remain alive

Question

Here how my code looks like:

var ws = null;

var _open = function(address) {
    ws = new WebSocket(address);
    ws.onopen = onOpen;
    ws.onclose = onClose;
    ws.onmessage = onMessage;
    ws.onerror = onError;
};

var close = function() {
    if (ws) ws.close();
};

var onOpen = function() {
    // do something
};

var onClose = function() {
    ws = null;
    retry();
};

var onError = function(event) {
    ws = null;
    retry();
};

var onMessage = function(event) {
    // do something
};

var retry = function() {
    setTimeout(function() { 
        // extract what I need from location.href
        var address = composeWsAddress(extractHostname(location.href));
        _open(address);
    }, 3000);
};

WebSocketClient = {
    init: function() {
        var address = composeWsAddress(extractHostname(location.href));
        _open(address);
    }
};

It should work in this way:

1. at start (init) it tries to connect
2. if fails (onError) it tries again after 3 s
3. if succeeds (onOpen) and then the connection closes (onClose) it tries again after 3 s

It works but on the WebSocket server I receive a number of new connections how many times they failed. For example, I launch my client application and after 30 s start the server. Now I have about 10 connections opened (one every 3 s).

Here I read I should not take care of "delete" each instance created by new WebSocket. Anyway I set it to null when the connection fails or closes.

So why it still keeps the old instances?