npm でインストールした ot.js の EditorSocketIOServer が動かない問題 ref: https://qiita.com/hato/items/8ad93c0fde62a145d6db

patch.js

var EditorSocketIOServer = require('ot/lib/editor-socketio-server');

/**
 * ot.js patch for socket.io >= 1.0
 * Copyright © 2012-2014 Tim Baumann, http://timbaumann.info
 * Released under the MIT License, https://github.com/Operational-Transformation/ot.js/blob/master/LICENSE
 */
{
    var EventEmitter = require('events').EventEmitter;
    var TextOperation = require('ot/lib/text-operation');
    var WrappedOperation = require('ot/lib/wrapped-operation');
    var Server = require('ot/lib/server');
    var Selection = require('ot/lib/selection');
    var util = require('util');

    EditorSocketIOServer.prototype.addClient = function (socket) {
        var self = this;
        socket
            .join(this.docId)
            .emit('doc', {
                str: this.document,
                revision: this.operations.length,
                clients: this.users
            })
            .on('operation', function (revision, operation, selection) {
                self.mayWrite(socket, function (mayWrite) {
                    if (!mayWrite) {
                        console.log("User doesn't have the right to edit.");
                        return;
                    }
                    self.onOperation(socket, revision, operation, selection);
                });
            })
            .on('selection', function (obj) {
                self.mayWrite(socket, function (mayWrite) {
                    if (!mayWrite) {
                        console.log("User doesn't have the right to edit.");
                        return;
                    }
                    self.updateSelection(socket, obj && Selection.fromJSON(obj));
                });
            })
            .on('disconnect', function () {
                console.log("Disconnect");
                socket.leave(self.docId);
                self.onDisconnect(socket);
                if (
                    (socket.manager && socket.manager.sockets.clients(self.docId).length === 0) || // socket.io <= 0.9
                    (socket.ns && Object.keys(socket.ns.connected).length === 0) // socket.io >= 1.0
                ) {
                    self.emit('empty-room');
                }
            });
    };
}