diff --git a/src/web/waiters/OperationsWaiter.mjs b/src/web/waiters/OperationsWaiter.mjs
index 151c6cea..2e8fcd87 100755
--- a/src/web/waiters/OperationsWaiter.mjs
+++ b/src/web/waiters/OperationsWaiter.mjs
@@ -288,8 +288,8 @@ class OperationsWaiter {
      * Get the children of categories and add event listener to them.
      */
     onKeyPress() {
-        let cat = document.getElementById("categories");
-        for(let i = 0; i < cat.children.length; i++){
+        const cat = document.getElementById("categories");
+        for (let i = 0; i < cat.children.length; i++){
             cat.children[i].addEventListener("keydown", this.keyboardEventHandler, false);
         };
     }