diff --git a/client/key/index.js b/client/key/index.js
index dfb5d96c..3f04fb40 100644
--- a/client/key/index.js
+++ b/client/key/index.js
@@ -25,6 +25,8 @@ const toggleVim = (keyCode) => {
     }
 };
 
+const isUndefined = (a) => typeof a === 'undefined';
+
 Chars([]);
 
 const {assign} = Object;
@@ -61,7 +63,7 @@ async function listener(event) {
     
     // strange chrome bug calles listener twice
     // in second time event misses a lot fields
-    if (typeof event.altKey === 'undefined')
+    if (isUndefined(event.altKey))
         return;
     
     const alt = event.altKey;
diff --git a/common/base64.js b/common/base64.js
index bc73b7f3..4d09b256 100644
--- a/common/base64.js
+++ b/common/base64.js
@@ -1,7 +1,9 @@
 'use strict';
 
+const isFn = (a) => typeof a === 'function';
+
 module.exports.btoa = (str) => {
-    if (typeof btoa === 'function')
+    if (isFn(btoa))
         return btoa(str);
     
     return Buffer
@@ -10,7 +12,7 @@ module.exports.btoa = (str) => {
 };
 
 module.exports.atob = (str) => {
-    if (typeof atob === 'function')
+    if (isFn(atob))
         return atob(str);
     
     return Buffer
diff --git a/server/cloudcmd.js b/server/cloudcmd.js
index 6faa6ed0..527fc633 100644
--- a/server/cloudcmd.js
+++ b/server/cloudcmd.js
@@ -45,6 +45,9 @@ const initAuth = currify(_initAuth);
 const notEmpty = (a) => a;
 const clean = (a) => a.filter(notEmpty);
 
+const isUndefined = (a) => typeof a === 'undefined';
+const isFn = (a) => typeof a === 'function';
+
 module.exports = (params) => {
     const p = params || {};
     const options = p.config || {};
@@ -98,7 +101,7 @@ function defaultValue(config, name, options) {
     const value = options[name];
     const previous = config(name);
     
-    if (typeof value === 'undefined')
+    if (isUndefined(value))
         return previous;
     
     return value;
@@ -106,7 +109,7 @@ function defaultValue(config, name, options) {
 
 module.exports._getPrefix = getPrefix;
 function getPrefix(prefix) {
-    if (typeof prefix === 'function')
+    if (isFn(prefix))
         return prefix() || '';
     
     return prefix || '';