diff --git a/.eslintrc.yaml b/.eslintrc.yaml
new file mode 100644
index 0000000..2ad47c5
--- /dev/null
+++ b/.eslintrc.yaml
@@ -0,0 +1,8 @@
+env:
+  node: true
+  es6: true
+
+extends: google
+
+rules:
+    comma-dangle: [2, only-multiline]
diff --git a/broker.js b/broker.js
index 54f9545..a1774df 100644
--- a/broker.js
+++ b/broker.js
@@ -1,17 +1,17 @@
 // Copyright 2017 DT42
 //
 // This file is part of BerryNet.
-// 
+//
 // BerryNet is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation, either version 3 of the License, or
 // (at your option) any later version.
-// 
+//
 // BerryNet is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
-// 
+//
 // You should have received a copy of the GNU General Public License
 // along with BerryNet.  If not, see <http://www.gnu.org/licenses/>.
 
diff --git a/camera.js b/camera.js
index e203378..2b9c519 100644
--- a/camera.js
+++ b/camera.js
@@ -1,17 +1,17 @@
 // Copyright 2017 DT42
-// 
+//
 // This file is part of BerryNet.
-// 
+//
 // BerryNet is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation, either version 3 of the License, or
 // (at your option) any later version.
-// 
+//
 // BerryNet is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
-// 
+//
 // You should have received a copy of the GNU General Public License
 // along with BerryNet.  If not, see <http://www.gnu.org/licenses/>.
 
@@ -28,11 +28,12 @@ const client = mqtt.connect(broker);
 const topicActionLog = config.topicActionLog;
 const topicActionInference = config.topicActionInference;
 const topicEventCamera = config.topicEventCamera;
-const topicNotifyEmail = config.topicNotifyEmail;
-const camera_uri = config.ipcameraSnapshot;
-const snapshot_file = '/tmp/snapshot.jpg';
-const camera_cmd = '/usr/bin/raspistill';
-const camera_args = ['-vf', '-hf', '-w', '1024', '-h', '768', '-o', snapshot_file];
+const cameraURI = config.ipcameraSnapshot;
+const snapshotFile = '/tmp/snapshot.jpg';
+const cameraCmd = '/usr/bin/raspistill';
+const cameraArgs = ['-vf', '-hf',
+  '-w', '1024', '-h', '768',
+  '-o', snapshotFile];
 
 function log(m) {
   client.publish(topicActionLog, m);
@@ -51,8 +52,8 @@ client.on('message', (t, m) => {
   if (action == 'snapshot_picam') {
     // Take a snapshot from RPi3 camera. The snapshot will be displayed
     // on dashboard.
-    spawnsync(camera_cmd, camera_args);
-    fs.readFile(snapshot_file, function(err, data) {
+    spawnsync(cameraCmd, cameraArgs);
+    fs.readFile(snapshotFile, function(err, data) {
       if (err) {
         log('camera client: cannot get image.');
       } else {
@@ -64,13 +65,13 @@ client.on('message', (t, m) => {
     // Take a snapshot from IP camera. The snapshot will be sent to
     // configured email address.
     request.get(
-      {uri: camera_uri, encoding: null},
+      {uri: cameraURI, encoding: null},
       (e, res, body) => {
         if (!e && res.statusCode == 200) {
-          log('camera client: publishing image.')
+          log('camera client: publishing image.');
           client.publish(topicActionInference, body);
         } else {
-          log('camera client: cannot get image.')
+          log('camera client: cannot get image.');
         }
       }
     );
diff --git a/config.js b/config.js
index 883a2b3..b4bf420 100644
--- a/config.js
+++ b/config.js
@@ -1,17 +1,17 @@
 // Copyright 2017 DT42
-// 
+//
 // This file is part of BerryNet.
-// 
+//
 // BerryNet is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation, either version 3 of the License, or
 // (at your option) any later version.
-// 
+//
 // BerryNet is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
-// 
+//
 // You should have received a copy of the GNU General Public License
 // along with BerryNet.  If not, see <http://www.gnu.org/licenses/>.
 
@@ -19,7 +19,7 @@
 
 const path = require('path');
 
-var config = {};
+let config = {};
 
 // system configs
 config.projectDir = __dirname;
@@ -27,7 +27,7 @@ config.inferenceEngine = 'detector';  // {classifier, detector}
 
 // gateway configs
 function padTopicBase(topic) {
-  return path.join(config.topicBase, topic)
+  return path.join(config.topicBase, topic);
 }
 
 config.snapshot = path.join(
diff --git a/journal.js b/journal.js
index 78c3ade..4d1882c 100644
--- a/journal.js
+++ b/journal.js
@@ -1,17 +1,17 @@
 // Copyright 2017 DT42
-// 
+//
 // This file is part of BerryNet.
-// 
+//
 // BerryNet is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation, either version 3 of the License, or
 // (at your option) any later version.
-// 
+//
 // BerryNet is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
-// 
+//
 // You should have received a copy of the GNU General Public License
 // along with BerryNet.  If not, see <http://www.gnu.org/licenses/>.
 
@@ -27,7 +27,7 @@ const client = mqtt.connect(broker);
 const topicActionLog = config.topicActionLog;
 const topicNotifyEmail = config.topicNotifyEmail;
 const topicDashboardLog = config.topicDashboardLog;
-const dashboard_pic_topic = config.topicDashboardSnapshot;
+const topicDashboardSnapshot = config.topicDashboardSnapshot;
 const snapshot = config.snapshot;
 
 let logs = [];
@@ -57,7 +57,7 @@ client.on('message', (t, m) => {
   if (t == topicNotifyEmail) {
     const filename = 'snapshot.jpg';
     saveBufferToImage(m, snapshot);
-    client.publish(dashboard_pic_topic, filename);
+    client.publish(topicDashboardSnapshot, filename);
     return;
   }
 
diff --git a/localimg.js b/localimg.js
index 24b7c93..09e2b3d 100644
--- a/localimg.js
+++ b/localimg.js
@@ -1,17 +1,17 @@
 // Copyright 2017 DT42
-// 
+//
 // This file is part of BerryNet.
-// 
+//
 // BerryNet is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation, either version 3 of the License, or
 // (at your option) any later version.
-// 
+//
 // BerryNet is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
-// 
+//
 // You should have received a copy of the GNU General Public License
 // along with BerryNet.  If not, see <http://www.gnu.org/licenses/>.
 
@@ -28,10 +28,8 @@
 
 'use strict';
 
-const mqtt = require('mqtt')
-const request = require('request')
-const spawnsync = require('child_process').spawnSync
-const fs = require('fs')
+const mqtt = require('mqtt');
+const fs = require('fs');
 const config = require('./config');
 
 const broker = config.brokerHost;
diff --git a/package.json b/package.json
index b12bd96..5179913 100644
--- a/package.json
+++ b/package.json
@@ -15,5 +15,9 @@
     "pino": "^2.13.0",
     "prompt": "^1.0.0",
     "request": "^2.79.0"
+  },
+  "devDependencies": {
+    "eslint": "^3.19.0",
+    "eslint-config-google": "^0.7.1"
   }
 }