change to es6 syntax with airbnb aslant coding style

.eslintrc

@@ -0,0 +1,3 @@
+{
+  "extends": "airbnb"
+}

app.js

@@ -1,72 +1,71 @@
-var express = require('express');
-var app = express();
-var fs = require('fs');
-var open = require('open');
-var options = {
+'use strict';
+
+const express = require('express');
+const app = express();
+const fs = require('fs');
+const open = require('open');
+const options = {
   key: fs.readFileSync('./fake-keys/privatekey.pem'),
-  cert: fs.readFileSync('./fake-keys/certificate.pem')
+  cert: fs.readFileSync('./fake-keys/certificate.pem'),
 };
-var serverPort = (process.env.PORT  || 4443);
-var https = require('https');
-var http = require('http');
-var server;
+const serverPort = (process.env.PORT || 4443);
+const https = require('https');
+const http = require('http');
+let server;
 if (process.env.LOCAL) {
   server = https.createServer(options, app);
 } else {
   server = http.createServer(app);
 }
-var io = require('socket.io')(server);
+const io = require('socket.io')(server);
 
-var roomList = {};
+const socketIdsInRoom = (name) => {
+  const socketIds = io.nsps['/'].adapter.rooms[name];
+  if (socketIds) {
+    const collection = [];
+    for (const key in socketIds) {
+      collection.push(key);
+    }
+    return collection;
+  }
+  return [];
+};
 
-app.get('/', function(req, res){
+app.get('/', (req, res) => {
   console.log('get /');
-  res.sendFile(__dirname + '/index.html');
+  res.sendFile(`${__dirname}/index.html`);
 });
-server.listen(serverPort, function(){
+
+server.listen(serverPort, () => {
   console.log('server up and running at %s port', serverPort);
   if (process.env.LOCAL) {
-    open('https://localhost:' + serverPort)
+    open(`https://localhost: ${serverPort}`);
   }
 });
 
-function socketIdsInRoom(name) {
-  var socketIds = io.nsps['/'].adapter.rooms[name];
-  if (socketIds) {
-    var collection = [];
-    for (var key in socketIds) {
-      collection.push(key);
-    }
-    return collection;
-  } else {
-    return [];
-  }
-}
-
-io.on('connection', function(socket){
+io.on('connection', (socket) => {
   console.log('connection');
-  socket.on('disconnect', function(){
+  socket.on('disconnect', () => {
     console.log('disconnect');
     if (socket.room) {
-      var room = socket.room;
+      const room = socket.room;
       io.to(room).emit('leave', socket.id);
       socket.leave(room);
     }
   });
 
-  socket.on('join', function(name, callback){
+  socket.on('join', (name, callback) => {
     console.log('join', name);
-    var socketIds = socketIdsInRoom(name);
+    const socketIds = socketIdsInRoom(name);
     callback(socketIds);
     socket.join(name);
     socket.room = name;
   });
 
-
-  socket.on('exchange', function(data){
+  socket.on('exchange', (data) => {
     console.log('exchange', data);
     data.from = socket.id;
-    var to = io.sockets.connected[data.to];
+    const to = io.sockets.connected[data.to];
     to.emit('exchange', data);
   });
 });

package.json

@@ -17,5 +17,12 @@
     "express": "^4.11.2",
     "open": "0.0.5",
     "socket.io": "1.3.4"
+  },
+  "devDependencies": {
+    "eslint": "^2.10.2",
+    "eslint-config-airbnb": "^9.0.1",
+    "eslint-plugin-import": "^1.10.2",
+    "eslint-plugin-jsx-a11y": "^1.5.5",
+    "eslint-plugin-react": "^5.2.2"
   }
 }

test.js

@@ -0,0 +1 @@
+console.log(`${__dirname}/index.html`);