diff --git a/src/lib/auth-utils.js b/src/lib/auth-utils.js
index 673c3c38c..67e7142dc 100644
--- a/src/lib/auth-utils.js
+++ b/src/lib/auth-utils.js
@@ -20,11 +20,11 @@ export function allow_action(action) {
 
 export function getDefaultPlugins() {
   return {
-    authenticate: function(user, password, cb) {
+    authenticate(user, password, cb) {
       cb(ErrorCode.getForbidden(API_ERROR.BAD_USERNAME_PASSWORD));
     },
 
-    add_user: function(user, password, cb) {
+    add_user(user, password, cb) {
       return cb(ErrorCode.getConflict(API_ERROR.BAD_USERNAME_PASSWORD));
     },
 
diff --git a/src/lib/config-utils.js b/src/lib/config-utils.js
index 59a0c5c11..2b712402d 100644
--- a/src/lib/config-utils.js
+++ b/src/lib/config-utils.js
@@ -30,7 +30,7 @@ export function normalizeUserlist(oldFormat: any, newFormat: any) {
     }
 
     // if it's a string, split it to array
-    if (typeof(arguments[i]) === 'string') {
+    if (_.isString(arguments[i])) {
       result.push(arguments[i].split(/\s+/));
     } else if (Array.isArray(arguments[i])) {
       result.push(arguments[i]);
@@ -60,7 +60,7 @@ export function uplinkSanityCheck(uplinks: UpLinksConfList, users: any = BLACKLI
 export function sanityCheckNames(item: string, users: any) {
   assert(item !== 'all' && item !== 'owner' && item !== 'anonymous' && item !== 'undefined' && item !== 'none', 'CONFIG: reserved uplink name: ' + item);
   assert(!item.match(/\s/), 'CONFIG: invalid uplink name: ' + item);
-  assert(users[item] == null, 'CONFIG: duplicate uplink name: ' + item);
+  assert(_.isNil(users[item]), 'CONFIG: duplicate uplink name: ' + item);
   users[item] = true;
 
   return users;
@@ -87,12 +87,7 @@ export function hasProxyTo(pkg: string, upLink: string, packages: PackageList):
   const matchedPkg: MatchedPackage = (getMatchedPackagesSpec(pkg, packages): MatchedPackage);
   const proxyList = typeof matchedPkg !== 'undefined' ? matchedPkg.proxy : [];
   if (proxyList) {
-    return proxyList.reduce((prev, curr) => {
-      if (upLink === curr) {
-        return true;
-      }
-      return prev;
-    }, false);
+    return proxyList.some((curr) => upLink === curr);
   }
 
   return false;
diff --git a/src/lib/config.js b/src/lib/config.js
index 823b57be4..c28673380 100644
--- a/src/lib/config.js
+++ b/src/lib/config.js
@@ -78,11 +78,11 @@ class Config implements AppConfig {
     this.packages = normalisePackageAccess(self.packages);
 
     // loading these from ENV if aren't in config
-    allowedEnvConfig.forEach((function(v) {
-      if (!(v in self)) {
-        self[v] = process.env[v] || process.env[v.toUpperCase()];
+    allowedEnvConfig.forEach((envConf) => {
+      if (!(envConf in self)) {
+        self[envConf] = process.env[envConf] || process.env[envConf.toUpperCase()];
       }
-    }));
+    });
 
     // unique identifier of self server (or a cluster), used to avoid loops
     if (!this.server_id) {
diff --git a/types/index.js b/types/index.js
index a4698005b..451a624c3 100644
--- a/types/index.js
+++ b/types/index.js
@@ -96,13 +96,6 @@ export interface IStorageHandler {
   _updateVersionsHiddenUpLink(versions: Versions, upLink: IProxy): void;
 }
 
-// export interface ConfigHandler {
-//   checkSecretKey(token: string): string;
-//   hasProxyTo(pkg: string, upLink: string): boolean;
-//   getMatchedPackagesSpec(storage: string): verdaccio$PackageAccess | void;
-//   [key: string]: number;
-// }
-
 export type StartUpConfig = {
   storage: string;
   self_path: string;