diff --git a/.prettierignore b/.prettierignore
index 3ff683f..b6f4cc4 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -1,3 +1,2 @@
+**/.*
 coverage
-.github
-.nyc_output
diff --git a/docs/_layouts/default.html b/docs/_layouts/default.html
index ba8235b..b06aa7e 100644
--- a/docs/_layouts/default.html
+++ b/docs/_layouts/default.html
@@ -87,11 +87,11 @@
 
     {% if site.google_analytics %}
     <script>
-      (function (i, s, o, g, r, a, m) {
+      (function(i, s, o, g, r, a, m) {
         i["GoogleAnalyticsObject"] = r;
         (i[r] =
           i[r] ||
-          function () {
+          function() {
             (i[r].q = i[r].q || []).push(arguments);
           }),
           (i[r].l = 1 * new Date());
diff --git a/docs/connect-logger.md b/docs/connect-logger.md
index 6dd5939..e75be9f 100644
--- a/docs/connect-logger.md
+++ b/docs/connect-logger.md
@@ -20,7 +20,7 @@ log4js.configure({
 var logger = log4js.getLogger("cheese");
 var app = express();
 app.use(log4js.connectLogger(logger, { level: "info" }));
-app.get("/", function (req, res) {
+app.get("/", function(req, res) {
   res.send("hello world");
 });
 app.listen(5000);
diff --git a/docs/layouts.md b/docs/layouts.md
index 5a8964d..fae80d1 100644
--- a/docs/layouts.md
+++ b/docs/layouts.md
@@ -161,7 +161,7 @@ log4js.configure({
         type: "pattern",
         pattern: "%d %p %c %x{user} %m%n",
         tokens: {
-          user: function (logEvent) {
+          user: function(logEvent) {
             return AuthLibrary.currentUser();
           },
         },
@@ -219,8 +219,8 @@ This example can also be found in examples/custom-layout.js.
 ```javascript
 const log4js = require("log4js");
 
-log4js.addLayout("json", function (config) {
-  return function (logEvent) {
+log4js.addLayout("json", function(config) {
+  return function(logEvent) {
     return JSON.stringify(logEvent) + config.separator;
   };
 });
diff --git a/examples/custom-layout.js b/examples/custom-layout.js
index 42b78d0..5cb00b6 100644
--- a/examples/custom-layout.js
+++ b/examples/custom-layout.js
@@ -3,7 +3,7 @@ const log4js = require('../lib/log4js');
 log4js.addLayout(
   'json',
   (config) =>
-    function (logEvent) {
+    function(logEvent) {
       return JSON.stringify(logEvent) + config.separator;
     }
 );
diff --git a/examples/hipchat-appender.js b/examples/hipchat-appender.js
index 8e04ba8..2c2e415 100644
--- a/examples/hipchat-appender.js
+++ b/examples/hipchat-appender.js
@@ -44,7 +44,7 @@ log4js.configure({
       hipchat_room: process.env.HIPCHAT_ROOM || '< Room ID or Name >',
       hipchat_from: 'Mr. Semantics',
       hipchat_notify: false,
-      hipchat_response_callback: function (err, response, body) {
+      hipchat_response_callback: function(err, response, body) {
         if (err || response.statusCode > 300) {
           throw new Error('hipchat-notifier failed');
         }
diff --git a/examples/patternLayout-tokens.js b/examples/patternLayout-tokens.js
index 764508b..9e8b010 100644
--- a/examples/patternLayout-tokens.js
+++ b/examples/patternLayout-tokens.js
@@ -8,7 +8,7 @@ log4js.configure({
         type: 'pattern',
         pattern: '%[%r (%x{pid}) %p %c -%] %m%n',
         tokens: {
-          pid: function () {
+          pid: function() {
             return process.pid;
           },
         },
diff --git a/lib/appenders/dateFile.js b/lib/appenders/dateFile.js
index 36811b3..46c9848 100644
--- a/lib/appenders/dateFile.js
+++ b/lib/appenders/dateFile.js
@@ -35,7 +35,7 @@ function appender(filename, pattern, layout, options, timezoneOffset) {
 
   const writer = openTheStream(filename, pattern, options);
 
-  const app = function (logEvent) {
+  const app = function(logEvent) {
     if (!writer.writable) {
       return;
     }
@@ -44,7 +44,7 @@ function appender(filename, pattern, layout, options, timezoneOffset) {
     }
   };
 
-  app.shutdown = function (complete) {
+  app.shutdown = function(complete) {
     writer.end('', 'utf-8', complete);
   };
 
diff --git a/lib/appenders/file.js b/lib/appenders/file.js
index 3f4f866..b408a62 100644
--- a/lib/appenders/file.js
+++ b/lib/appenders/file.js
@@ -83,7 +83,7 @@ function fileAppender(
 
   let writer = openTheStream(file, logSize, numBackups, options);
 
-  const app = function (loggingEvent) {
+  const app = function(loggingEvent) {
     if (!writer.writable) {
       return;
     }
@@ -100,18 +100,18 @@ function fileAppender(
     }
   };
 
-  app.reopen = function () {
+  app.reopen = function() {
     writer.end(() => {
       writer = openTheStream(file, logSize, numBackups, options);
     });
   };
 
-  app.sighupHandler = function () {
+  app.sighupHandler = function() {
     debug('SIGHUP handler called.');
     app.reopen();
   };
 
-  app.shutdown = function (complete) {
+  app.shutdown = function(complete) {
     sighupListeners.delete(app);
     if (sighupListeners.size === 0 && mainSighupListenerStarted) {
       process.removeListener('SIGHUP', mainSighupHandler);
diff --git a/lib/appenders/multiprocess.js b/lib/appenders/multiprocess.js
index 06d9fb5..2b8d3c7 100644
--- a/lib/appenders/multiprocess.js
+++ b/lib/appenders/multiprocess.js
@@ -78,7 +78,7 @@ function logServer(config, actualAppender, levels) {
     return actualAppender(event);
   }
 
-  app.shutdown = function (cb) {
+  app.shutdown = function(cb) {
     debug('(master) master shutdown called, closing server');
     server.close(cb);
   };
@@ -108,9 +108,8 @@ function workerAppender(config) {
 
   function createSocket() {
     debug(
-      `(worker) worker appender creating socket to ${
-        config.loggerHost || 'localhost'
-      }:${config.loggerPort || 5000}`
+      `(worker) worker appender creating socket to ${config.loggerHost ||
+        'localhost'}:${config.loggerPort || 5000}`
     );
     socket = net.createConnection(
       config.loggerPort || 5000,
@@ -142,7 +141,7 @@ function workerAppender(config) {
       buffer.push(loggingEvent);
     }
   }
-  log.shutdown = function (cb) {
+  log.shutdown = function(cb) {
     debug('(worker) worker shutdown called');
     if (buffer.length && shutdownAttempts) {
       debug('(worker) worker buffer has items, waiting 100ms to empty');
diff --git a/lib/appenders/recording.js b/lib/appenders/recording.js
index ca90e07..3468f63 100644
--- a/lib/appenders/recording.js
+++ b/lib/appenders/recording.js
@@ -3,7 +3,7 @@ const debug = require('debug')('log4js:recording');
 const recordedEvents = [];
 
 function configure() {
-  return function (logEvent) {
+  return function(logEvent) {
     debug(
       `received logEvent, number of events now ${recordedEvents.length + 1}`
     );
diff --git a/lib/appenders/tcp.js b/lib/appenders/tcp.js
index 5a9854a..06c51bb 100644
--- a/lib/appenders/tcp.js
+++ b/lib/appenders/tcp.js
@@ -23,9 +23,8 @@ function appender(config, layout) {
 
   function createSocket() {
     debug(
-      `appender creating socket to ${config.host || 'localhost'}:${
-        config.port || 5000
-      }`
+      `appender creating socket to ${config.host ||
+        'localhost'}:${config.port || 5000}`
     );
     endMsg = `${config.endMsg || '__LOG4JS__'}`;
     socket = net.createConnection(
@@ -62,7 +61,7 @@ function appender(config, layout) {
     }
   }
 
-  log.shutdown = function (cb) {
+  log.shutdown = function(cb) {
     debug('shutdown called');
     if (buffer.length && shutdownAttempts) {
       debug('buffer has items, waiting 100ms to empty');
@@ -80,7 +79,7 @@ function appender(config, layout) {
 
 function configure(config, layouts) {
   debug(`configure with config = ${config}`);
-  let layout = function (loggingEvent) {
+  let layout = function(loggingEvent) {
     return loggingEvent.serialise();
   };
   if (config.layout) {
diff --git a/lib/layouts.js b/lib/layouts.js
index 8e5325b..8884162 100644
--- a/lib/layouts.js
+++ b/lib/layouts.js
@@ -130,8 +130,7 @@ function dummyLayout(loggingEvent) {
  */
 function patternLayout(pattern, tokens) {
   const TTCC_CONVERSION_PATTERN = '%r %p %c - %m%n';
-  const regex =
-    /%(-?[0-9]+)?(\.?-?[0-9]+)?([[\]cdhmnprzxXyflos%])(\{([^}]+)\})?|([^%]+)/;
+  const regex = /%(-?[0-9]+)?(\.?-?[0-9]+)?([[\]cdhmnprzxXyflos%])(\{([^}]+)\})?|([^%]+)/;
 
   pattern = pattern || TTCC_CONVERSION_PATTERN;
 
@@ -272,7 +271,7 @@ function patternLayout(pattern, tokens) {
 
     // support for ESM as it uses url instead of path for file
     /* istanbul ignore next: unsure how to simulate ESM for test coverage */
-    const convertFileURLToPath = function (filepath) {
+    const convertFileURLToPath = function(filepath) {
       const urlPrefix = 'file://';
       if (filepath.startsWith(urlPrefix)) {
         // https://nodejs.org/api/url.html#urlfileurltopathurl
@@ -386,7 +385,7 @@ function patternLayout(pattern, tokens) {
     return replacement;
   }
 
-  return function (loggingEvent) {
+  return function(loggingEvent) {
     let formattedString = '';
     let result;
     let searchString = pattern;
diff --git a/lib/logger.js b/lib/logger.js
index 14385d6..d979caf 100644
--- a/lib/logger.js
+++ b/lib/logger.js
@@ -141,11 +141,11 @@ function addLevelMethods(target) {
   );
   const isLevelMethod = levelMethod[0].toUpperCase() + levelMethod.slice(1);
 
-  Logger.prototype[`is${isLevelMethod}Enabled`] = function () {
+  Logger.prototype[`is${isLevelMethod}Enabled`] = function() {
     return this.isLevelEnabled(level);
   };
 
-  Logger.prototype[levelMethod] = function (...args) {
+  Logger.prototype[levelMethod] = function(...args) {
     this.log(level, ...args);
   };
 }
diff --git a/package-lock.json b/package-lock.json
index 3714ad2..6817ea1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5185,9 +5185,9 @@
       }
     },
     "prettier": {
-      "version": "2.7.1",
-      "resolved": "https://registry.npmjs.org/prettier/-/prettier-2.7.1.tgz",
-      "integrity": "sha512-ujppO+MkdPqoVINuDFDRLClm7D78qbDt0/NR+wp5FqEZOoTNAjPHWj17QRhu7geIHJfcNhRk1XVQmF8Bp3ye+g==",
+      "version": "1.19.1",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-1.19.1.tgz",
+      "integrity": "sha512-s7PoyDv/II1ObgQunCbB9PdLmUcBZcnWOcxDh7O0N/UwDEsHyqkW+Qh28jW+mVuCdx7gLB0BotYI1Y6uI9iyew==",
       "dev": true
     },
     "proxyquire": {
diff --git a/package.json b/package.json
index 37d78fe..d3b7f75 100644
--- a/package.json
+++ b/package.json
@@ -34,8 +34,8 @@
   },
   "scripts": {
     "prepare": "is-ci || husky install",
-    "pretest": "prettier --check . && eslint \"lib/**/*.js\" \"test/**/*.js\"",
-    "prettier:fix": "prettier --write .",
+    "pretest": "prettier --check \"**/*.*\" && eslint \"lib/**/*.js\" \"test/**/*.js\"",
+    "prettier:fix": "prettier --write \"**/*.*\"",
     "test": "tap \"test/tap/**/*.js\" --cov --timeout=45",
     "typings": "tsc -p types/tsconfig.json"
   },
@@ -66,7 +66,7 @@
     "husky": "^8.0.1",
     "is-ci": "^3.0.1",
     "nyc": "^15.1.0",
-    "prettier": "^2.7.1",
+    "prettier": "^1.19.1",
     "proxyquire": "^2.1.3",
     "tap": "^16.3.0",
     "typescript": "^4.7.4"
@@ -74,6 +74,20 @@
   "browser": {
     "os": false
   },
+  "prettier": {
+    "trailingComma": "es5",
+    "arrowParens": "always",
+    "overrides": [
+      {
+        "files": [
+          "*.cjs"
+        ],
+        "options": {
+          "parser": "typescript"
+        }
+      }
+    ]
+  },
   "tap": {
     "check-coverage": true
   },
diff --git a/test/tap/configuration-inheritance-test.js b/test/tap/configuration-inheritance-test.js
index ae49422..a25716d 100644
--- a/test/tap/configuration-inheritance-test.js
+++ b/test/tap/configuration-inheritance-test.js
@@ -55,8 +55,9 @@ test('log4js category inherit all appenders from direct parent', (batch) => {
       log4js.configure(config);
 
       const child1CategoryName = 'catA.catB.cat1';
-      const child1Appenders =
-        categories.appendersForCategory(child1CategoryName);
+      const child1Appenders = categories.appendersForCategory(
+        child1CategoryName
+      );
       const child1Level = categories.getLevelForCategory(child1CategoryName);
 
       t.equal(child1Appenders.length, 1, 'inherited 1 appender');
@@ -67,8 +68,9 @@ test('log4js category inherit all appenders from direct parent', (batch) => {
       t.equal(child1Level.levelStr, 'DEBUG', 'child level overrides parent');
 
       const child2CategoryName = 'catA.catB.cat2';
-      const child2Appenders =
-        categories.appendersForCategory(child2CategoryName);
+      const child2Appenders = categories.appendersForCategory(
+        child2CategoryName
+      );
       const child2Level = categories.getLevelForCategory(child2CategoryName);
 
       t.ok(child2Appenders);
@@ -122,8 +124,9 @@ test('log4js category inherit all appenders from direct parent', (batch) => {
     );
 
     const firstParentName = 'catA.catB';
-    const firstParentAppenders =
-      categories.appendersForCategory(firstParentName);
+    const firstParentAppenders = categories.appendersForCategory(
+      firstParentName
+    );
 
     t.ok(firstParentAppenders);
     t.equal(firstParentAppenders.length, 2, 'ended up with 2 appenders');
diff --git a/test/tap/configuration-validation-test.js b/test/tap/configuration-validation-test.js
index cd0ad06..1633d5e 100644
--- a/test/tap/configuration-validation-test.js
+++ b/test/tap/configuration-validation-test.js
@@ -318,8 +318,9 @@ test('log4js configuration validation', (batch) => {
         `${path.join(mainPath, '../../node_modules/nyc/bin/cheese')}`
       ] = testAppender('correct', result);
       // in tap v15, the main path is at root of log4js (run `DEBUG=log4js:appenders npm test > /dev/null` to check)
-      sandboxConfig.requires[`${path.join(mainPath, '../../cheese')}`] =
-        testAppender('correct', result);
+      sandboxConfig.requires[
+        `${path.join(mainPath, '../../cheese')}`
+      ] = testAppender('correct', result);
       // in node v6, there's an extra layer of node modules for some reason, so add this one to work around it
       sandboxConfig.requires[
         `${path.join(
diff --git a/test/tap/connect-logger-test.js b/test/tap/connect-logger-test.js
index 4119f31..f73f101 100644
--- a/test/tap/connect-logger-test.js
+++ b/test/tap/connect-logger-test.js
@@ -8,10 +8,10 @@ class MockLogger {
   constructor() {
     this.level = levels.TRACE;
     this.messages = [];
-    this.log = function (level, message) {
+    this.log = function(level, message) {
       this.messages.push({ level, message });
     };
-    this.isLevelEnabled = function (level) {
+    this.isLevelEnabled = function(level) {
       return level.isGreaterThanOrEqualTo(this.level);
     };
   }
diff --git a/test/tap/connect-nolog-test.js b/test/tap/connect-nolog-test.js
index 1d780a7..338cccb 100644
--- a/test/tap/connect-nolog-test.js
+++ b/test/tap/connect-nolog-test.js
@@ -9,11 +9,11 @@ class MockLogger {
     this.messages = [];
     this.level = levels.TRACE;
 
-    this.log = function (level, message) {
+    this.log = function(level, message) {
       this.messages.push({ level, message });
     };
 
-    this.isLevelEnabled = function (level) {
+    this.isLevelEnabled = function(level) {
       return level.isGreaterThanOrEqualTo(this.level);
     };
   }
diff --git a/test/tap/default-settings-test.js b/test/tap/default-settings-test.js
index f772038..3694fb3 100644
--- a/test/tap/default-settings-test.js
+++ b/test/tap/default-settings-test.js
@@ -3,8 +3,9 @@ const debug = require('debug');
 const sandbox = require('@log4js-node/sandboxed-module');
 
 test('default settings', (batch) => {
-  const originalListener =
-    process.listeners('warning')[process.listeners('warning').length - 1];
+  const originalListener = process.listeners('warning')[
+    process.listeners('warning').length - 1
+  ];
   const warningListener = (error) => {
     if (error.name === 'DeprecationWarning') {
       if (
@@ -48,7 +49,7 @@ test('default settings', (batch) => {
         name: 'stdout',
         appender() {
           // deprecated
-          return function (evt) {
+          return function(evt) {
             output.push(evt);
           };
         },
diff --git a/test/tap/file-sighup-test.js b/test/tap/file-sighup-test.js
index e8f3c03..aa1d262 100644
--- a/test/tap/file-sighup-test.js
+++ b/test/tap/file-sighup-test.js
@@ -13,8 +13,9 @@ test('file appender single SIGHUP handler', (t) => {
   const initialListeners = process.listenerCount('SIGHUP');
 
   let warning;
-  const originalListener =
-    process.listeners('warning')[process.listeners('warning').length - 1];
+  const originalListener = process.listeners('warning')[
+    process.listeners('warning').length - 1
+  ];
   const warningListener = (error) => {
     if (
       error.type === 'SIGHUP' &&
diff --git a/test/tap/layouts-test.js b/test/tap/layouts-test.js
index 8a77b48..f240eec 100644
--- a/test/tap/layouts-test.js
+++ b/test/tap/layouts-test.js
@@ -249,8 +249,9 @@ test('log4js layouts', (batch) => {
   });
 
   batch.test('patternLayout', (t) => {
-    const originalListener =
-      process.listeners('warning')[process.listeners('warning').length - 1];
+    const originalListener = process.listeners('warning')[
+      process.listeners('warning').length - 1
+    ];
     const warningListener = (error) => {
       if (error.name === 'DeprecationWarning') {
         if (
@@ -923,7 +924,7 @@ test('log4js layouts', (batch) => {
     t.test('should be able to add a layout', (assert) => {
       layouts.addLayout('test_layout', (config) => {
         assert.equal(config, 'test_config');
-        return function (logEvent) {
+        return function(logEvent) {
           return `TEST LAYOUT >${logEvent.data}`;
         };
       });
diff --git a/test/tap/logger-test.js b/test/tap/logger-test.js
index 62c5834..3baa296 100644
--- a/test/tap/logger-test.js
+++ b/test/tap/logger-test.js
@@ -255,7 +255,7 @@ test('../../lib/logger', (batch) => {
 
   batch.test('should correctly change the parseCallStack function', (t) => {
     const logger = new Logger('stack');
-    const parseFunction = function () {
+    const parseFunction = function() {
       return {
         functionName: 'test function name',
         fileName: 'test file name',
diff --git a/test/tap/logging-test.js b/test/tap/logging-test.js
index 4461d14..ea7e394 100644
--- a/test/tap/logging-test.js
+++ b/test/tap/logging-test.js
@@ -121,7 +121,7 @@ test('log4js', (batch) => {
               return null;
             }
 
-            thing.shutdown = function (cb) {
+            thing.shutdown = function(cb) {
               events.shutdownCalled.push(true);
               cb();
             };
@@ -196,7 +196,7 @@ test('log4js', (batch) => {
         './file': {
           configure(configuration) {
             appenderConfig = configuration;
-            return function () {};
+            return function() {};
           },
         },
       },
@@ -220,7 +220,7 @@ test('log4js', (batch) => {
     const fakeStdoutAppender = {
       configure() {
         this.required = true;
-        return function (evt) {
+        return function(evt) {
           fakeStdoutAppender.evt = evt;
         };
       },
diff --git a/test/tap/multi-file-appender-test.js b/test/tap/multi-file-appender-test.js
index 937ccda..42f5959 100644
--- a/test/tap/multi-file-appender-test.js
+++ b/test/tap/multi-file-appender-test.js
@@ -134,8 +134,8 @@ test('multiFile appender', (batch) => {
               layouts
             );
             const originalShutdown = fileAppender.shutdown;
-            fileAppender.shutdown = function (complete) {
-              const onCallback = function () {
+            fileAppender.shutdown = function(complete) {
+              const onCallback = function() {
                 complete(error);
               };
               originalShutdown(onCallback);
diff --git a/test/tap/tcp-appender-test.js b/test/tap/tcp-appender-test.js
index 068ff82..07f1fe6 100644
--- a/test/tap/tcp-appender-test.js
+++ b/test/tap/tcp-appender-test.js
@@ -181,7 +181,7 @@ test('TCP Appender', (batch) => {
     log4js.addLayout(
       'json',
       () =>
-        function (logEvent) {
+        function(logEvent) {
           return JSON.stringify({
             time: logEvent.startTime,
             message: logEvent.data[0],
diff --git a/types/test.ts b/types/test.ts
index ad6ae4a..ccfed3b 100644
--- a/types/test.ts
+++ b/types/test.ts
@@ -35,7 +35,7 @@ log4js.configure({
 log4js.addLayout(
   'json',
   (config) =>
-    function (logEvent) {
+    function(logEvent) {
       return JSON.stringify(logEvent) + config.separator;
     }
 );