diff --git a/js/src/dom/event-handler.js b/js/src/dom/event-handler.js
index a31ed333c9..413aa6e284 100644
--- a/js/src/dom/event-handler.js
+++ b/js/src/dom/event-handler.js
@@ -20,7 +20,7 @@ const customEvents = {
   mouseenter: 'mouseover',
   mouseleave: 'mouseout'
 }
-const customEventsRegex = /^(mouseenter|mouseleave)/i
+
 const nativeEvents = new Set([
   'click',
   'dblclick',
@@ -150,7 +150,7 @@ function addHandler(element, originalTypeEvent, handler, delegationFunction, one
 
   // in case of mouseenter or mouseleave wrap the handler within a function that checks for its DOM position
   // this prevents the handler from being dispatched the same way as mouseover or mouseout does
-  if (customEventsRegex.test(originalTypeEvent)) {
+  if (originalTypeEvent in customEvents) {
     const wrapFunction = fn => {
       return function (event) {
         if (!event.relatedTarget || (event.relatedTarget !== event.delegateTarget && !event.delegateTarget.contains(event.relatedTarget))) {