diff --git a/.eslintignore b/.eslintignore
new file mode 100644
index 0000000..37f3e66
--- /dev/null
+++ b/.eslintignore
@@ -0,0 +1,3 @@
+**/node_modules/**
+react-es6-popup/**/dist
+mocha-client-tests
diff --git a/.eslintrc.json b/.eslintrc.json
new file mode 100644
index 0000000..bd5191f
--- /dev/null
+++ b/.eslintrc.json
@@ -0,0 +1,22 @@
+{
+  "root": true,
+  "parserOptions": {
+    "ecmaVersion": 6
+  },
+  "env": {
+    "browser": true,
+    "es6": true,
+    "webextensions": true
+  },
+  "extends": [
+    "eslint:recommended"
+  ],
+  "rules": {
+    "no-console": 0,
+    "no-unused-vars": ["warn", { "vars": "all", "args": "all" } ],
+    "no-undef": ["warn"],
+    "no-proto": ["error"],
+    "prefer-arrow-callback": ["warn"],
+    "prefer-spread": ["warn"]
+  }
+}
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..3c3629e
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+node_modules
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..96c06b2
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,7 @@
+language: node_js
+node_js:
+    - "8"
+sudo: false
+
+script:
+    - "npm test"
diff --git a/README.md b/README.md
index 505ef63..426b57a 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# webextensions-examples
+# webextensions-examples [![Build Status](https://travis-ci.org/mdn/webextensions-examples.svg?branch=master)](https://travis-ci.org/mdn/webextensions-examples)
 
 [https://github.com/mdn/webextensions-examples](https://github.com/mdn/webextensions-examples)
 
diff --git a/annotate-page/sidebar/panel.js b/annotate-page/sidebar/panel.js
index f4fdb46..2af8505 100644
--- a/annotate-page/sidebar/panel.js
+++ b/annotate-page/sidebar/panel.js
@@ -4,14 +4,14 @@ const contentBox = document.querySelector("#content");
 /*
 Make the content box editable as soon as the user mouses over the sidebar.
 */
-window.addEventListener("mouseover", (e) => {
+window.addEventListener("mouseover", () => {
   contentBox.setAttribute("contenteditable", true);
 });
 
 /*
 When the user mouses out, save the current contents of the box.
 */
-window.addEventListener("mouseout", (e) => {
+window.addEventListener("mouseout", () => {
   contentBox.setAttribute("contenteditable", false);
   browser.tabs.query({windowId: myWindowId, active: true}).then((tabs) => {
     let contentToStore = {};
diff --git a/apply-css/background.js b/apply-css/background.js
index 7e936a0..3c0b1aa 100644
--- a/apply-css/background.js
+++ b/apply-css/background.js
@@ -51,7 +51,7 @@ When first loaded, initialize the page action for all tabs.
 */
 var gettingAllTabs = browser.tabs.query({});
 gettingAllTabs.then((tabs) => {
-  for (tab of tabs) {
+  for (let tab of tabs) {
     initializePageAction(tab);
   }
 });
diff --git a/chill-out/background.js b/chill-out/background.js
index bbf453f..d29d949 100644
--- a/chill-out/background.js
+++ b/chill-out/background.js
@@ -69,6 +69,6 @@ browser.alarms.onAlarm.addListener((alarm) => {
 /*
 On page action click, navigate the corresponding tab to the cat gifs.
 */
-browser.pageAction.onClicked.addListener(function () {
+browser.pageAction.onClicked.addListener(() => {
   browser.tabs.update({url: CATGIFS});
 });
diff --git a/commands/background.js b/commands/background.js
index 825c559..a54dc95 100644
--- a/commands/background.js
+++ b/commands/background.js
@@ -12,7 +12,7 @@
  */
 var gettingAllCommands = browser.commands.getAll();
 gettingAllCommands.then((commands) => {
-  for (command of commands) {
+  for (let command of commands) {
     console.log(command);
   }
 });
diff --git a/context-menu-copy-link-with-types/background.js b/context-menu-copy-link-with-types/background.js
index b8d1505..9152745 100644
--- a/context-menu-copy-link-with-types/background.js
+++ b/context-menu-copy-link-with-types/background.js
@@ -3,7 +3,7 @@ browser.contextMenus.create({
     title: "Copy link to clipboard",
     contexts: ["link"],
 });
-browser.contextMenus.onClicked.addListener(function(info, tab) {
+browser.contextMenus.onClicked.addListener((info, tab) => {
     if (info.menuItemId === "copy-link-to-clipboard") {
         // Examples: text and HTML to be copied.
         const text = "This is text: " + info.linkUrl;
@@ -22,7 +22,7 @@ browser.contextMenus.onClicked.addListener(function(info, tab) {
 
         browser.tabs.executeScript({
             code: "typeof copyToClipboard === 'function';",
-        }).then(function(results) {
+        }).then((results) => {
             // The content script's last expression will be true if the function
             // has been defined. If this is not the case, then we need to run
             // clipboard-helper.js to define function copyToClipboard.
@@ -31,11 +31,11 @@ browser.contextMenus.onClicked.addListener(function(info, tab) {
                     file: "clipboard-helper.js",
                 });
             }
-        }).then(function() {
+        }).then(() => {
             return browser.tabs.executeScript(tab.id, {
                 code,
             });
-        }).catch(function(error) {
+        }).catch((error) => {
             // This could happen if the extension is not allowed to run code in
             // the page, for example if the tab is a privileged page.
             console.error("Failed to copy text: " + error);
diff --git a/context-menu-demo/background.js b/context-menu-demo/background.js
index 98f43a1..359c57b 100644
--- a/context-menu-demo/background.js
+++ b/context-menu-demo/background.js
@@ -2,7 +2,7 @@
 Called when the item has been created, or when creation failed due to an error.
 We'll just log success/failure here.
 */
-function onCreated(n) {
+function onCreated() {
   if (browser.runtime.lastError) {
     console.log(`Error: ${browser.runtime.lastError}`);
   } else {
@@ -127,7 +127,7 @@ function updateCheckUncheck() {
 The click event listener, where we perform the appropriate action given the
 ID of the menu item that was clicked.
 */
-browser.contextMenus.onClicked.addListener(function(info, tab) {
+browser.contextMenus.onClicked.addListener((info, tab) => {
   switch (info.menuItemId) {
     case "log-selection":
       console.log(info.selectionText);
diff --git a/embedded-webextension-bootstrapped/.eslintrc.json b/embedded-webextension-bootstrapped/.eslintrc.json
new file mode 100644
index 0000000..30e26e9
--- /dev/null
+++ b/embedded-webextension-bootstrapped/.eslintrc.json
@@ -0,0 +1,8 @@
+{
+  "env": {
+    "browser": true,
+    "es6": true,
+    "amd": true,
+    "webextensions": true
+  }
+}
diff --git a/embedded-webextension-sdk/.eslintrc.json b/embedded-webextension-sdk/.eslintrc.json
new file mode 100644
index 0000000..30e26e9
--- /dev/null
+++ b/embedded-webextension-sdk/.eslintrc.json
@@ -0,0 +1,8 @@
+{
+  "env": {
+    "browser": true,
+    "es6": true,
+    "amd": true,
+    "webextensions": true
+  }
+}
diff --git a/emoji-substitution/emojiMap.js b/emoji-substitution/emojiMap.js
index 16c689e..b2f1b9e 100644
--- a/emoji-substitution/emojiMap.js
+++ b/emoji-substitution/emojiMap.js
@@ -2,6 +2,8 @@
  * This file contains the Map of word --> emoji substitutions.
  */
 
+/* exported sortedEmojiMap */
+
 let dictionary = new Map();
 dictionary.set('apple', '🍎');
 dictionary.set('banana', '🍌');
diff --git a/emoji-substitution/substitute.js b/emoji-substitution/substitute.js
index c886063..39203db 100644
--- a/emoji-substitution/substitute.js
+++ b/emoji-substitution/substitute.js
@@ -3,6 +3,8 @@
  * all occurrences of each mapped word with its emoji counterpart.
  */
 
+/*global sortedEmojiMap*/
+
 // emojiMap.js defines the 'sortedEmojiMap' variable.
 // Referenced here to reduce confusion.
 const emojiMap = sortedEmojiMap;
diff --git a/google-userinfo/background/authorize.js b/google-userinfo/background/authorize.js
index 633c41b..b49bb72 100644
--- a/google-userinfo/background/authorize.js
+++ b/google-userinfo/background/authorize.js
@@ -1,3 +1,5 @@
+/* exported getAccessToken */
+
 const REDIRECT_URL = browser.identity.getRedirectURL();
 const CLIENT_ID = "YOUR-CLIENT-ID";
 const SCOPES = ["openid", "email", "profile"];
diff --git a/google-userinfo/background/main.js b/google-userinfo/background/main.js
index ac70222..9ddf1fb 100644
--- a/google-userinfo/background/main.js
+++ b/google-userinfo/background/main.js
@@ -1,3 +1,5 @@
+/*global getAccessToken*/
+
 function notifyUser(user) {
   browser.notifications.create({
     "type": "basic",
diff --git a/google-userinfo/background/userinfo.js b/google-userinfo/background/userinfo.js
index 84a5427..5f7ac1d 100644
--- a/google-userinfo/background/userinfo.js
+++ b/google-userinfo/background/userinfo.js
@@ -2,6 +2,9 @@
 Fetch the user's info, passing in the access token in the Authorization
 HTTP request header.
 */
+
+/* exported getUserInfo */
+
 function getUserInfo(accessToken) {
   const requestURL = "https://www.googleapis.com/oauth2/v1/userinfo?alt=json";
   const requestHeaders = new Headers();
diff --git a/history-deleter/history.js b/history-deleter/history.js
index 11a1dff..798f8db 100644
--- a/history-deleter/history.js
+++ b/history-deleter/history.js
@@ -7,7 +7,7 @@ function get_hostname(url) {
 }
 
 function set_domain(domain) {
-  spans = document.getElementsByClassName('domain');
+  const spans = document.getElementsByClassName('domain');
   [].slice.call(spans).forEach((span) => {
     span.textContent = domain;
   });
@@ -65,7 +65,7 @@ function clearAll(e) {
     // Loop through them and delete them one by one.
     var searchingHistory = browser.history.search({text: hostname})
     searchingHistory.then((results) => {
-        for (k = 0; k < results.length; k++) {
+        for (let k of results) {
           browser.history.deleteUrl({url: results[k].url});
         }
         // Clear out the UI.
diff --git a/list-cookies/cookies.js b/list-cookies/cookies.js
index 74c5a84..db2fc8e 100644
--- a/list-cookies/cookies.js
+++ b/list-cookies/cookies.js
@@ -1,6 +1,6 @@
 function showCookiesForTab(tabs) {
   //get the first tab object in the array
-  tab = tabs.pop();
+  let tab = tabs.pop();
 
   //get all cookies in the domain
   var gettingAllCookies = browser.cookies.getAll({url: tab.url});
@@ -14,22 +14,22 @@ function showCookiesForTab(tabs) {
 
     if (cookies.length > 0) {
       //add an <li> item with the name and value of the cookie to the list
-      for (cookie of cookies) {
-        var li = document.createElement("li");
-        var content = document.createTextNode(cookie.name + ": "+ cookie.value);
+      for (let cookie of cookies) {
+        let li = document.createElement("li");
+        let content = document.createTextNode(cookie.name + ": "+ cookie.value);
         li.appendChild(content);
         cookieList.appendChild(li);
       }
     } else {
-      var p = document.createElement("p");
-      var content = document.createTextNode("No cookies in this tab.");
-      var parent = cookieList.parentNode;
+      let p = document.createElement("p");
+      let content = document.createTextNode("No cookies in this tab.");
+      let parent = cookieList.parentNode;
 
       p.appendChild(content);
       parent.appendChild(p);
     }
   });
-};
+}
 
 //get active tab to run an callback function.
 //it sends to our callback an array of tab objects
diff --git a/mocha-client-tests/.eslintrc.json b/mocha-client-tests/.eslintrc.json
new file mode 100644
index 0000000..30e26e9
--- /dev/null
+++ b/mocha-client-tests/.eslintrc.json
@@ -0,0 +1,8 @@
+{
+  "env": {
+    "browser": true,
+    "es6": true,
+    "amd": true,
+    "webextensions": true
+  }
+}
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..019418f
--- /dev/null
+++ b/package.json
@@ -0,0 +1,32 @@
+{
+  "name": "webextensions-examples",
+  "title": "WebExtensions Examples",
+  "version": "1.0.0",
+  "description": "Example Firefox add-ons created using the WebExtensions API",
+  "devDependencies": {
+    "eslint": "^3.19.0"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/mdn/webextensions-examples.git"
+  },
+  "scripts": {
+    "test": "eslint .",
+    "lint": "eslint ."
+  },
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/mdn/webextensions-examples/issues"
+  },
+  "keywords": [
+    "webextensions",
+    "webextensions-apis",
+    "mdn",
+    "firefox",
+    "mozilla"
+  ],
+  "homepage": "https://developer.mozilla.org/Add-ons/WebExtensions/Examples",
+  "dependencies": {
+    "babel-eslint": "^7.2.3"
+  }
+}
diff --git a/page-to-extension-messaging/content-script.js b/page-to-extension-messaging/content-script.js
index 01646c9..418fa46 100644
--- a/page-to-extension-messaging/content-script.js
+++ b/page-to-extension-messaging/content-script.js
@@ -2,7 +2,7 @@
 Listen for messages from the page.
 If the message was from the page script, show an alert.
 */
-window.addEventListener("message", function(event) {
+window.addEventListener("message", (event) => {
   if (event.source == window &&
       event.data &&
       event.data.direction == "from-page-script") {
diff --git a/permissions/.eslintrc.json b/permissions/.eslintrc.json
new file mode 100644
index 0000000..22c3ada
--- /dev/null
+++ b/permissions/.eslintrc.json
@@ -0,0 +1,5 @@
+{
+  "parserOptions": {
+    "ecmaVersion": 8
+  }
+}
diff --git a/proxy-blocker/background/proxy-handler.js b/proxy-blocker/background/proxy-handler.js
index 098089c..aabcd89 100644
--- a/proxy-blocker/background/proxy-handler.js
+++ b/proxy-blocker/background/proxy-handler.js
@@ -15,7 +15,7 @@ browser.proxy.onProxyError.addListener(error => {
 });
 
 // Initialize the proxy
-function handleInit(message) {
+function handleInit() {
   // update the proxy whenever stored settings change
   browser.storage.onChanged.addListener((newSettings) => {
     browser.runtime.sendMessage(newSettings.blockedHosts.newValue, {toProxyScript: true});
diff --git a/proxy-blocker/proxy/proxy-script.js b/proxy-blocker/proxy/proxy-script.js
index 135295c..31343e6 100644
--- a/proxy-blocker/proxy/proxy-script.js
+++ b/proxy-blocker/proxy/proxy-script.js
@@ -1,3 +1,5 @@
+/* exported FindProxyForURL */
+
 var blockedHosts = [];
 const allow = "DIRECT 1234";
 const deny = "PROXY 127.0.0.1:65535";
diff --git a/quicknote/popup/quicknote.js b/quicknote/popup/quicknote.js
index b94c29e..04d5a81 100644
--- a/quicknote/popup/quicknote.js
+++ b/quicknote/popup/quicknote.js
@@ -27,7 +27,7 @@ function initialize() {
   var gettingAllStorageItems = browser.storage.local.get(null);
   gettingAllStorageItems.then((results) => {
     var noteKeys = Object.keys(results);
-    for(noteKey of noteKeys) {
+    for (let noteKey of noteKeys) {
       var curValue = results[noteKey];
       displayNote(noteKey,curValue);
     }
@@ -88,8 +88,8 @@ function displayNote(title, body) {
 
   /* set up listener for the delete functionality */
 
-  deleteBtn.addEventListener('click',function(e){
-    evtTgt = e.target;
+  deleteBtn.addEventListener('click',(e) => {
+    const evtTgt = e.target;
     evtTgt.parentNode.parentNode.parentNode.removeChild(evtTgt.parentNode.parentNode);
     browser.storage.local.remove(title);
   })
@@ -125,24 +125,24 @@ function displayNote(title, body) {
 
   /* set up listeners for the update functionality */
 
-  noteH.addEventListener('click',function(){
+  noteH.addEventListener('click',() => {
     noteDisplay.style.display = 'none';
     noteEdit.style.display = 'block';
   })
 
-  notePara.addEventListener('click',function(){
+  notePara.addEventListener('click',() => {
     noteDisplay.style.display = 'none';
     noteEdit.style.display = 'block';
   }) 
 
-  cancelBtn.addEventListener('click',function(){
+  cancelBtn.addEventListener('click',() => {
     noteDisplay.style.display = 'block';
     noteEdit.style.display = 'none';
     noteTitleEdit.value = title;
     noteBodyEdit.value = body;
   })
 
-  updateBtn.addEventListener('click',function(){
+  updateBtn.addEventListener('click',() => {
     if(noteTitleEdit.value !== title || noteBodyEdit.value !== body) {
       updateNote(title,noteTitleEdit.value,noteBodyEdit.value);
       note.parentNode.removeChild(note);
diff --git a/react-es6-popup/.eslintrc.json b/react-es6-popup/.eslintrc.json
new file mode 100644
index 0000000..bc30d96
--- /dev/null
+++ b/react-es6-popup/.eslintrc.json
@@ -0,0 +1,15 @@
+{
+  "parserOptions": {
+    "ecmaVersion": 6,
+    "sourceType": "module",
+    "ecmaFeatures": {
+      "jsx": true
+    }
+  },
+  "env": {
+    "browser": true,
+    "es6": true,
+    "amd": true,
+    "webextensions": true
+  }
+}
diff --git a/selection-to-clipboard/content-script.js b/selection-to-clipboard/content-script.js
index 8fb2598..1b78c5b 100644
--- a/selection-to-clipboard/content-script.js
+++ b/selection-to-clipboard/content-script.js
@@ -1,7 +1,7 @@
 /*
 copy the selected text to clipboard
 */
-function copySelection(e) {
+function copySelection() {
     var selectedText = window.getSelection().toString().trim();
 
     if (selectedText) {
diff --git a/tabs-tabs-tabs/tabs.js b/tabs-tabs-tabs/tabs.js
index dba3dfc..27e7a1b 100644
--- a/tabs-tabs-tabs/tabs.js
+++ b/tabs-tabs-tabs/tabs.js
@@ -47,7 +47,7 @@ function getCurrentWindowTabs() {
   return browser.tabs.query({currentWindow: true});
 }
 
-document.addEventListener("click", function(e) {
+document.addEventListener("click", (e) => {
   function callOnActiveTab(callback) {
     getCurrentWindowTabs().then((tabs) => {
       for (var tab of tabs) {
@@ -163,7 +163,7 @@ document.addEventListener("click", function(e) {
   // Currently (11/2/2016) only supported by Chrome
   else if (e.target.id === "tabs-highlight") { // highlights current tab and next tab (cycles back to first tab if current tab is the last one)
     callOnActiveTab((tab, tabs) => {
-      next = (tab.index+1) % tabs.length;
+      let next = (tab.index+1) % tabs.length;
       browser.tabs.highlight({tabs:[tab.index, next]});
     });
   }
@@ -173,7 +173,7 @@ document.addEventListener("click", function(e) {
 
     chrome.tabs.query({
       currentWindow: true
-    }, function(tabs) {
+    }, (tabs) => {
       for (var tab of tabs) {
         if (tab.id === tabId) {
           chrome.tabs.update(tabId, {
@@ -188,7 +188,7 @@ document.addEventListener("click", function(e) {
 });
 
 //onRemoved listener. fired when tab is removed
-browser.tabs.onRemoved.addListener(function(tabId, removeInfo){
+browser.tabs.onRemoved.addListener((tabId, removeInfo) => {
   console.log(`The tab with id: ${tabId}, is closing`);
 
   if(removeInfo.isWindowClosing) {
@@ -199,7 +199,7 @@ browser.tabs.onRemoved.addListener(function(tabId, removeInfo){
 });
 
 //onMoved listener. fired when tab is moved into the same window
-browser.tabs.onMoved.addListener(function(tabId, moveInfo){
+browser.tabs.onMoved.addListener((tabId, moveInfo) => {
   var startIndex = moveInfo.fromIndex;
   var endIndex = moveInfo.toIndex;
   console.log(`Tab with id: ${tabId} moved from index: ${startIndex} to index: ${endIndex}`);
diff --git a/user-agent-rewriter/popup/choose_ua.js b/user-agent-rewriter/popup/choose_ua.js
index baaddaf..91dbbc9 100644
--- a/user-agent-rewriter/popup/choose_ua.js
+++ b/user-agent-rewriter/popup/choose_ua.js
@@ -4,7 +4,7 @@ If the user clicks on an element which has the class "ua-choice":
 * fetch the element's textContent: for example, "IE 11"
 * pass it into the background page's setUaString() function
 */
-document.addEventListener("click", function(e) {
+document.addEventListener("click", (e) => {
   if (!e.target.classList.contains("ua-choice")) {
     return;
   }
diff --git a/webpack-modules/.eslintrc.json b/webpack-modules/.eslintrc.json
new file mode 100644
index 0000000..30e26e9
--- /dev/null
+++ b/webpack-modules/.eslintrc.json
@@ -0,0 +1,8 @@
+{
+  "env": {
+    "browser": true,
+    "es6": true,
+    "amd": true,
+    "webextensions": true
+  }
+}
diff --git a/window-manipulator/window.js b/window-manipulator/window.js
index d6e36eb..a659b48 100644
--- a/window-manipulator/window.js
+++ b/window-manipulator/window.js
@@ -26,48 +26,48 @@ document.addEventListener("click", (e) => {
   }
 
   else if (e.target.id === "window-create-normal") {
-    var createData = {};
-    var creating = browser.windows.create(createData);
+    let createData = {};
+    let creating = browser.windows.create(createData);
     creating.then(() => {
       console.log("The normal window has been created");
     });
   }
 
   else if (e.target.id === "window-create-incognito") {
-    var createData = {
+    let createData = {
       incognito: true,
     };
-    var creating = browser.windows.create(createData);
+    let creating = browser.windows.create(createData);
     creating.then(() => {
       console.log("The incognito window has been created");
     });
   }
 
   else if (e.target.id === "window-create-panel") {
-    var createData = {
+    let createData = {
       type: "panel",
     };
-    var creating = browser.windows.create(createData);
+    let creating = browser.windows.create(createData);
     creating.then(() => {
       console.log("The panel has been created");
     });
   }
 
   else if (e.target.id === "window-create-detached-panel") {
-    var createData = {
+    let createData = {
       type: "detached_panel",
     };
-    var creating = browser.windows.create(createData);
+    let creating = browser.windows.create(createData);
     creating.then(() => {
       console.log("The detached panel has been created");
     });
   }
 
   else if (e.target.id === "window-create-popup") {
-    var createData = {
+    let createData = {
       type: "popup",
     };
-    var creating = browser.windows.create(createData);
+    let creating = browser.windows.create(createData);
     creating.then(() => {
       console.log("The popup has been created");
     });