diff --git a/gulpfile.js b/gulpfile.js
index d3ab4a5..c380307 100755
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -23,7 +23,7 @@ function clean() {
 }
 
 function jsWebpack(done) {
-  exec('webpack-cli --display-error-details --bail --colors', function(
+  exec('webpack-cli --display-error-details --bail --colors', function (
     err,
     stdout,
     stderr
@@ -95,7 +95,9 @@ async function fonts(done) {
   });
 
   await new Promise(resolve => {
-    src('node_modules/fontsource-roboto/files/roboto-latin-@(400|500|700)-normal.woff2')
+    src(
+      'node_modules/fontsource-roboto/files/roboto-latin-@(400|500|700)-normal.woff2'
+    )
       .pipe(dest(path.join(distDir, 'src/fonts/files')))
       .on('error', done)
       .on('finish', resolve);
@@ -104,7 +106,7 @@ async function fonts(done) {
 
 async function locale(done) {
   const localesRootDir = path.join(__dirname, 'src/_locales');
-  const localeDirs = readdirSync(localesRootDir).filter(function(file) {
+  const localeDirs = readdirSync(localesRootDir).filter(function (file) {
     return lstatSync(path.join(localesRootDir, file)).isDirectory();
   });
   for (const localeDir of localeDirs) {
@@ -193,7 +195,7 @@ See the LICENSE file for further information.
 function zip(done) {
   exec(
     `web-ext build -s dist/${targetEnv} -a artifacts/${targetEnv} -n '{name}-{version}-${targetEnv}.zip' --overwrite-dest`,
-    function(err, stdout, stderr) {
+    function (err, stdout, stderr) {
       console.log(stdout);
       console.log(stderr);
       done(err);
@@ -204,7 +206,7 @@ function zip(done) {
 function inspect(done) {
   exec(
     `webpack --profile --json > report.json && webpack-bundle-analyzer report.json dist/firefox/src && sleep 10 && rm report.{json,html}`,
-    function(err, stdout, stderr) {
+    function (err, stdout, stderr) {
       console.log(stdout);
       console.log(stderr);
       done(err);
diff --git a/src/content/initReset.js b/src/content/initReset.js
index d51a7d9..891db99 100644
--- a/src/content/initReset.js
+++ b/src/content/initReset.js
@@ -1,7 +1,7 @@
 function initReset(challengeUrl) {
   const script = document.createElement('script');
-  script.onload = function(e) {
-    e.target.remove();
+  script.onload = function (ev) {
+    ev.target.remove();
     document.dispatchEvent(
       new CustomEvent('___resetCaptcha', {detail: challengeUrl})
     );
@@ -11,14 +11,14 @@ function initReset(challengeUrl) {
 }
 
 function addListener() {
-  const onMessage = function(request) {
+  const onMessage = function (request) {
     if (request.id === 'resetCaptcha') {
       removeCallbacks();
       initReset(request.challengeUrl);
     }
   };
 
-  const removeCallbacks = function() {
+  const removeCallbacks = function () {
     window.clearTimeout(timeoutId);
     chrome.runtime.onMessage.removeListener(onMessage);
   };
diff --git a/src/content/reset.js b/src/content/reset.js
index 7a790c3..4617ca4 100644
--- a/src/content/reset.js
+++ b/src/content/reset.js
@@ -1,5 +1,5 @@
-(function() {
-  const reset = function(challengeUrl) {
+(function () {
+  const reset = function (challengeUrl) {
     for (const [k, client] of Object.entries(___grecaptcha_cfg.clients)) {
       for (const [_, items] of Object.entries(client)) {
         for (const [_, v] of Object.entries(items)) {
@@ -12,14 +12,14 @@
     }
   };
 
-  const onMessage = function(e) {
-    e.stopImmediatePropagation();
+  const onMessage = function (ev) {
+    ev.stopImmediatePropagation();
     window.clearTimeout(timeoutId);
 
-    reset(e.detail);
+    reset(ev.detail);
   };
 
-  const timeoutId = window.setTimeout(function() {
+  const timeoutId = window.setTimeout(function () {
     document.removeEventListener('___resetCaptcha', onMessage, {
       capture: true,
       once: true
diff --git a/src/contribute/App.vue b/src/contribute/App.vue
index 49dcc91..9c081d1 100644
--- a/src/contribute/App.vue
+++ b/src/contribute/App.vue
@@ -15,7 +15,7 @@ export default {
     [Contribute.name]: Contribute
   },
 
-  data: function() {
+  data: function () {
     return {
       extName: getText('extensionName'),
       extSlug: 'buster',
@@ -23,7 +23,7 @@ export default {
     };
   },
 
-  created: function() {
+  created: function () {
     document.title = getText('pageTitle', [
       getText('pageTitle_contribute'),
       this.extName
diff --git a/src/contribute/main.js b/src/contribute/main.js
index 2d519b3..d4da16e 100755
--- a/src/contribute/main.js
+++ b/src/contribute/main.js
@@ -2,7 +2,7 @@ import Vue from 'vue';
 
 import App from './App';
 
-var vm = new Vue({
+new Vue({
   el: '#app',
   render: h => h(App)
 });
diff --git a/src/options/App.vue b/src/options/App.vue
index 5a6a0c0..2aa78be 100644
--- a/src/options/App.vue
+++ b/src/options/App.vue
@@ -306,7 +306,7 @@ export default {
       try {
         await pingClientApp();
         this.clientAppInstalled = true;
-      } catch (e) {
+      } catch (err) {
         if (!this.installGuideUrl) {
           this.installGuideUrl =
             'https://github.com/dessant/buster/wiki/Installing-the-client-app';
diff --git a/src/options/main.js b/src/options/main.js
index ead13f4..0f80e42 100644
--- a/src/options/main.js
+++ b/src/options/main.js
@@ -6,9 +6,9 @@ async function init() {
   try {
     await document.fonts.load('400 14px Roboto');
     await document.fonts.load('500 14px Roboto');
-  } catch (e) {}
+  } catch (err) {}
 
-  const vm = new Vue({
+  new Vue({
     el: '#app',
     render: h => h(App)
   });
diff --git a/src/setup/App.vue b/src/setup/App.vue
index 0148254..274c39d 100644
--- a/src/setup/App.vue
+++ b/src/setup/App.vue
@@ -76,7 +76,7 @@ export default {
     [TextField.name]: TextField
   },
 
-  data: function() {
+  data: function () {
     const urlParams = new URL(window.location.href).searchParams;
     const apiURL = new URL('http://127.0.0.1/api/v1');
     apiURL.port = urlParams.get('port');
@@ -100,7 +100,7 @@ export default {
   methods: {
     getText,
 
-    getExtensionId: function() {
+    getExtensionId: function () {
       let id = browser.runtime.id;
       if (targetEnv !== 'firefox') {
         const scheme = window.location.protocol;
@@ -110,7 +110,7 @@ export default {
       return id;
     },
 
-    setLocation: async function() {
+    setLocation: async function () {
       try {
         await this.location();
       } catch (err) {
@@ -119,7 +119,7 @@ export default {
       }
     },
 
-    runInstall: async function() {
+    runInstall: async function () {
       this.isInstalling = true;
 
       try {
@@ -144,7 +144,7 @@ export default {
       }
     },
 
-    location: async function() {
+    location: async function () {
       const data = new FormData();
       data.append('session', this.session);
       data.append('browser', this.browser);
@@ -167,7 +167,7 @@ export default {
       }
     },
 
-    install: async function() {
+    install: async function () {
       const data = new FormData();
       data.append('session', this.session);
       data.append('appDir', this.appDir);
@@ -194,7 +194,7 @@ export default {
     }
   },
 
-  created: async function() {
+  created: async function () {
     this.browser = (await browser.runtime.sendMessage({id: 'getBrowser'})).name;
 
     await this.setLocation();
diff --git a/src/setup/main.js b/src/setup/main.js
index 143264d..d6d8cbf 100644
--- a/src/setup/main.js
+++ b/src/setup/main.js
@@ -6,9 +6,9 @@ async function init() {
   try {
     await document.fonts.load('400 14px Roboto');
     await document.fonts.load('500 14px Roboto');
-  } catch (e) {}
+  } catch (err) {}
 
-  const vm = new Vue({
+  new Vue({
     el: '#app',
     render: h => h(App)
   });
diff --git a/src/solve/main.js b/src/solve/main.js
index d87696c..65f2b2c 100644
--- a/src/solve/main.js
+++ b/src/solve/main.js
@@ -279,10 +279,10 @@ async function solve(simulateUserInput, clickEvent) {
   }
 
   if (simulateUserInput) {
-    const muteAudio = function() {
+    const muteAudio = function () {
       audioEl.muted = true;
     };
-    const unmuteAudio = function() {
+    const unmuteAudio = function () {
       removeCallbacks();
       audioEl.muted = false;
     };
@@ -296,7 +296,7 @@ async function solve(simulateUserInput, clickEvent) {
       once: true
     });
 
-    const removeCallbacks = function() {
+    const removeCallbacks = function () {
       window.clearTimeout(timeoutId);
       audioEl.removeEventListener('playing', muteAudio, {
         capture: true,
diff --git a/src/utils/app.js b/src/utils/app.js
index c8cfe8c..aac2539 100755
--- a/src/utils/app.js
+++ b/src/utils/app.js
@@ -28,7 +28,7 @@ function getOptionLabels(data, scope = 'optionValue') {
   const labels = {};
   for (const [group, items] of Object.entries(data)) {
     labels[group] = [];
-    items.forEach(function(value) {
+    items.forEach(function (value) {
       labels[group].push({
         id: value,
         label: getText(`${scope}_${group}_${value}`)
@@ -57,24 +57,24 @@ function sendNativeMessage(port, message, {timeout = 10000} = {}) {
     const id = uuidv4();
     message.id = id;
 
-    const messageCallback = function(msg) {
+    const messageCallback = function (msg) {
       if (msg.id !== id) {
         return;
       }
       removeListeners();
       resolve(msg);
     };
-    const errorCallback = function() {
+    const errorCallback = function () {
       removeListeners();
       reject('No response from native app');
     };
-    const removeListeners = function() {
+    const removeListeners = function () {
       window.clearTimeout(timeoutId);
       port.onMessage.removeListener(messageCallback);
       port.onDisconnect.removeListener(errorCallback);
     };
 
-    const timeoutId = window.setTimeout(function() {
+    const timeoutId = window.setTimeout(function () {
       errorCallback();
     }, timeout);
 
diff --git a/src/utils/common.js b/src/utils/common.js
index 4daac50..d039901 100644
--- a/src/utils/common.js
+++ b/src/utils/common.js
@@ -45,7 +45,7 @@ async function getBrowser() {
   let name, version;
   try {
     ({name, version} = await browser.runtime.getBrowserInfo());
-  } catch (e) {}
+  } catch (err) {}
 
   if (!name) {
     ({name, version} = Bowser.getParser(
@@ -74,7 +74,7 @@ function waitForElement(selector, {timeout = 10000} = {}) {
       return;
     }
 
-    const observer = new MutationObserver(function(mutations, obs) {
+    const observer = new MutationObserver(function (mutations, obs) {
       const el = document.querySelector(selector);
       if (el) {
         obs.disconnect();
@@ -88,7 +88,7 @@ function waitForElement(selector, {timeout = 10000} = {}) {
       subtree: true
     });
 
-    const timeoutId = window.setTimeout(function() {
+    const timeoutId = window.setTimeout(function () {
       observer.disconnect();
       resolve();
     }, timeout);
@@ -130,7 +130,7 @@ async function scriptsAllowed(tabId, frameId = 0) {
       code: 'true;'
     });
     return true;
-  } catch (e) {}
+  } catch (err) {}
 }
 
 async function functionInContext(