diff --git a/js/src/dom/event-handler.js b/js/src/dom/event-handler.js
index 71f61e9c8..1034d2906 100644
--- a/js/src/dom/event-handler.js
+++ b/js/src/dom/event-handler.js
@@ -208,9 +208,8 @@ function removeHandler(element, events, typeEvent, handler, delegationSelector)
 function removeNamespacedHandlers(element, events, typeEvent, namespace) {
   const storeElementEvent = events[typeEvent] || {}
 
-  for (const handlerKey of Object.keys(storeElementEvent)) {
+  for (const [handlerKey, event] of Object.entries(storeElementEvent)) {
     if (handlerKey.includes(namespace)) {
-      const event = storeElementEvent[handlerKey]
       removeHandler(element, events, typeEvent, event.originalHandler, event.delegationSelector)
     }
   }
@@ -258,11 +257,10 @@ const EventHandler = {
     }
 
     const storeElementEvent = events[typeEvent] || {}
-    for (const keyHandlers of Object.keys(storeElementEvent)) {
+    for (const [keyHandlers, event] of Object.entries(storeElementEvent)) {
       const handlerKey = keyHandlers.replace(stripUidRegex, '')
 
       if (!inNamespace || originalTypeEvent.includes(handlerKey)) {
-        const event = storeElementEvent[keyHandlers]
         removeHandler(element, events, typeEvent, event.originalHandler, event.delegationSelector)
       }
     }
@@ -295,10 +293,10 @@ const EventHandler = {
 
     // merge custom information in our event
     if (typeof args !== 'undefined') {
-      for (const key of Object.keys(args)) {
+      for (const [key, value] of Object.entries(args)) {
         Object.defineProperty(evt, key, {
           get() {
-            return args[key]
+            return value
           }
         })
       }
diff --git a/js/src/tooltip.js b/js/src/tooltip.js
index 407fa5930..45b3aca48 100644
--- a/js/src/tooltip.js
+++ b/js/src/tooltip.js
@@ -625,9 +625,9 @@ class Tooltip extends BaseComponent {
   _getDelegateConfig() {
     const config = {}
 
-    for (const key in this._config) {
-      if (this.constructor.Default[key] !== this._config[key]) {
-        config[key] = this._config[key]
+    for (const [key, value] of Object.entries(this._config)) {
+      if (this.constructor.Default[key] !== value) {
+        config[key] = value
       }
     }
 
diff --git a/js/src/util/config.js b/js/src/util/config.js
index 19d02955d..dd9e37ba9 100644
--- a/js/src/util/config.js
+++ b/js/src/util/config.js
@@ -46,8 +46,7 @@ class Config {
   }
 
   _typeCheckConfig(config, configTypes = this.constructor.DefaultType) {
-    for (const property of Object.keys(configTypes)) {
-      const expectedTypes = configTypes[property]
+    for (const [property, expectedTypes] of Object.entries(configTypes)) {
       const value = config[property]
       const valueType = isElement(value) ? 'element' : toType(value)