dist/reconnecting-websocket-amd.js
function () {
                var bytes = this._messageQueue.reduce(function (acc, message) {
                    if (typeof message === 'string') {
                        acc += message.length; // not byte size
                    }
                    else if (message instanceof Blob) {
                        acc += message.size;
                    }
                    else {
                        acc += message.byteLength;
                    }
                    return acc;
                }, 0);
                return bytes + (this._ws ? this._ws.bufferedAmount : 0);
            }
function () {
                var bytes = this._messageQueue.reduce(function (acc, message) {
                    if (typeof message === 'string') {
                        acc += message.length; // not byte size
                    }
                    else if (message instanceof Blob) {
                        acc += message.size;
                    }
                    else {
                        acc += message.byteLength;
                    }
                    return acc;
                }, 0);
                return bytes + (this._ws ? this._ws.bufferedAmount : 0);
            }
The number of bytes of data that have been queued using calls to send() but not yet
transmitted to the network. This value resets to zero once all queued data has been sent.
This value does not reset to zero when the connection is closed; if you keep calling send(),
this will continue to climb. Read only