diff --git a/src/drivers/chrome/js/driver.js b/src/drivers/chrome/js/driver.js
index 3b0fa13ff..d2ec6ae29 100644
--- a/src/drivers/chrome/js/driver.js
+++ b/src/drivers/chrome/js/driver.js
@@ -54,7 +54,7 @@
 					firstRun = true;
 
 					// Set defaults
-					for ( option in defaults ) {
+					for ( var option in defaults ) {
 						localStorage[option] = defaults[option];
 					}
 				} else if ( version !== localStorage['version'] && parseInt(localStorage['upgradeMessage'], 10) ) {
@@ -189,7 +189,7 @@
 
 			if ( count > 0 ) {
 				// Find the main application to display
-				var i, appName, found = false;
+				var appName, found = false;
 
 				w.driver.categoryOrder.forEach(function(match) {
 					for ( appName in w.detected[url] ) {
diff --git a/src/drivers/chrome/js/options.js b/src/drivers/chrome/js/options.js
index 7ee9be839..92d1fe3f7 100644
--- a/src/drivers/chrome/js/options.js
+++ b/src/drivers/chrome/js/options.js
@@ -15,9 +15,9 @@ document.addEventListener('DOMContentLoaded', function() {
 		},
 
 		load: function() {
-			for ( option in options.opts ) {
-				if ( value = localStorage[option] ) {
-					options.opts[option] = value;
+			for ( var option in options.opts ) {
+				if ( localStorage[option] ) {
+					options.opts[option] = localStorage[option];
 				}
 			}
 
diff --git a/src/drivers/firefox/data/js/tab.js b/src/drivers/firefox/data/js/tab.js
index eafd3c507..72719ec2b 100644
--- a/src/drivers/firefox/data/js/tab.js
+++ b/src/drivers/firefox/data/js/tab.js
@@ -1,11 +1,7 @@
 (function() {
-	var lastEnv = [];
-
 	try {
 		if ( document && document.contentType === 'text/html' ) {
-			var
-				html = new XMLSerializer().serializeToString(document),
-				env = []; // TODO: Remove, `env` not used in this scope?
+			var html = new XMLSerializer().serializeToString(document),
 
 			self.port.emit('log', html);
 
diff --git a/src/drivers/webextension/js/driver.js b/src/drivers/webextension/js/driver.js
index 9519d680d..f5583a670 100644
--- a/src/drivers/webextension/js/driver.js
+++ b/src/drivers/webextension/js/driver.js
@@ -54,7 +54,7 @@
 					firstRun = true;
 
 					// Set defaults
-					for ( option in defaults ) {
+					for ( var option in defaults ) {
 						localStorage[option] = defaults[option];
 					}
 				} else if ( version !== localStorage['version'] && parseInt(localStorage['upgradeMessage'], 10) ) {
@@ -195,7 +195,7 @@
 
 			if ( count > 0 ) {
 				// Find the main application to display
-				var i, appName, found = false;
+				var appName, found = false;
 
 				w.driver.categoryOrder.forEach(function(match) {
 					for ( appName in w.detected[url] ) {
diff --git a/src/drivers/webextension/js/iframe.js b/src/drivers/webextension/js/iframe.js
index 70f6fc408..fcf40539f 100644
--- a/src/drivers/webextension/js/iframe.js
+++ b/src/drivers/webextension/js/iframe.js
@@ -112,8 +112,6 @@ var exports = {};
 				try {
 					dict[key] = window.decodeURIComponent(val);
 				} catch (e) {
-
-					continue;
 				}
 			}
 			return dict;
@@ -307,6 +305,7 @@ var exports = {};
 				return div;
 			}
 		}
+		return null;
 	};
 
 	TopSearcher.prototype._jumpedOut = function(el) {
@@ -988,6 +987,7 @@ var exports = {};
 				}
 			}
 		}
+		return null;
 	}
 
 	function onPostMessage(event) {
diff --git a/src/wappalyzer.js b/src/wappalyzer.js
index 7bddd6930..8eb4f289f 100644
--- a/src/wappalyzer.js
+++ b/src/wappalyzer.js
@@ -242,7 +242,7 @@ var wappalyzer = (function() {
 		 */
 		analyze: function(hostname, url, data) {
 			var
-				i, j, app, confidence, type, regexMeta, regexScript, match, content, meta, header, version, id,
+				i, app, confidence, type, regexMeta, regexScript, match, content, meta, header, version, id,
 				profiler     = new Profiler(),
 				apps         = {},
 				excludes     = [],