diff --git a/lib/server.js b/lib/server.js
index 0f951050..9cad1280 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -1,40 +1,37 @@
 'use strict';
 
-var DIR_LIB             = './',
-    DIR_SERVER          = DIR_LIB + 'server/',
-    
-    http                = require('http'),
-    opn                 = require('opn'),
-    
-    cloudcmd            = require(DIR_LIB + 'cloudcmd'),
-    exit                = require(DIR_SERVER + 'exit'),
-    config              = require(DIR_SERVER + 'config'),
-    prefixer            = require(DIR_SERVER + 'prefixer'),
-    express             = require('express'),
-    tryRequire          = require('tryrequire'),
-    logger              = tryRequire('morgan'),
-    io                  = require('socket.io'),
-    squad               = require('squad'),
-    apart               = require('apart'),
-    prefix              = squad(prefixer, apart(config, 'prefix'));
+const DIR_LIB = './';
+const DIR_SERVER = DIR_LIB + 'server/';
 
-/**
- * start server function
- *
- */
-module.exports  = function(options) {
-    var server,
-        port    =   process.env.PORT            ||  /* c9           */
-                    process.env.VCAP_APP_PORT   ||  /* cloudfoundry */
-                    config('port'),
-        
-        ip      =   process.env.IP              ||  /* c9           */
-                    config('ip')                ||
-                    '0.0.0.0',
-        
-        app     = express();
+const cloudcmd = require(DIR_LIB + 'cloudcmd');
+
+const exit = require(DIR_SERVER + 'exit');
+const config = require(DIR_SERVER + 'config');
+const prefixer = require(DIR_SERVER + 'prefixer');
+
+const http = require('http');
+const opn = require('opn');
+const express = require('express');
+const io = require('socket.io');
+const squad = require('squad');
+const apart = require('apart');
+
+const tryRequire = require('tryrequire');
+const logger = tryRequire('morgan');
+
+const prefix = squad(prefixer, apart(config, 'prefix'));
+
+module.exports = (options) => {
+    const port = process.env.PORT            ||  /* c9           */
+                 process.env.VCAP_APP_PORT   ||  /* cloudfoundry */
+                 config('port');
     
-    server          = http.createServer(app);
+    const ip =  process.env.IP               ||  /* c9           */
+                config('ip')                 ||
+                '0.0.0.0';
+    
+    const app = express();
+    const server = http.createServer(app);
     
     if (logger)
         app.use(logger('dev'));
@@ -49,18 +46,20 @@ module.exports  = function(options) {
     if (port < 0 || port > 65535)
         exit('cloudcmd --port: %s', 'port number could be 1..65535, 0 means any available port');
     
-    server.listen(port, ip, function() {
-        var host = config('ip') || 'localhost';
-        var port0 = port || server.address().port;
-        var url = 'http://' + host + ':' + port0 + prefix() + '/';
+    server.listen(port, ip, () => {
+        const host = config('ip') || 'localhost';
+        const port0 = port || server.address().port;
+        const url = `http://${host}:${port0}${prefix()}/`;
         
         console.log('url:', url);
         
-        if (config('open'))
-            opn(url);
+        if (!config('open'))
+            return;
+        
+        opn(url);
     });
     
-    server.on('error', function(error) {
+    server.on('error', error => {
         exit('cloudcmd --port: %s', error.message);
     });
 };