diff --git a/asset/js/functions.js b/asset/js/functions.js
new file mode 100644
index 00000000..359720d6
--- /dev/null
+++ b/asset/js/functions.js
@@ -0,0 +1,21 @@
+(function (root, factory) {
+    "use strict";
+
+    if (typeof define === "function" && define.icinga) {
+        define(["exports"], factory);
+    } else {
+        factory(root.iplWebFunctions = root.iplWebFunctions || {});
+    }
+}(self, function (exports) {
+    /**
+     * Checks if the given keyboard event represents a special key press.
+     *
+     * @param {KeyboardEvent} event - The keyboard event to check.
+     * @returns {boolean} True if the event represents a special key press, false otherwise.
+     */
+    function isSpecialKeyPress(event) {
+        return event.key.length > 1 || event.ctrlKey || event.metaKey;
+    }
+
+    exports.isSpecialKeyPress = isSpecialKeyPress;
+}));
diff --git a/asset/js/widget/BaseInput.js b/asset/js/widget/BaseInput.js
index 360d5026..87598e03 100644
--- a/asset/js/widget/BaseInput.js
+++ b/asset/js/widget/BaseInput.js
@@ -1,4 +1,4 @@
-define(["../notjQuery", "Completer"], function ($, Completer) {
+define(["../notjQuery", "../functions", "Completer"], function ($, functions, Completer) {
 
     "use strict";
 
@@ -803,7 +803,7 @@ define(["../notjQuery", "Completer"], function ($, Completer) {
             let input = event.target;
             let termIndex = Number(input.parentNode.dataset.index);
 
-            if (this.hasSyntaxError(input) && ! (/[A-Z]/.test(event.key.charAt(0)) || event.ctrlKey || event.metaKey)) {
+            if (this.hasSyntaxError(input) && ! functions.isSpecialKeyPress(event)) {
                 // Clear syntax error flag if the user types entirely new input after having selected the entire input
                 // (This way the input isn't empty but switches from input to input immediately, causing the clearing
                 // in onInput to not work)
diff --git a/asset/js/widget/Completer.js b/asset/js/widget/Completer.js
index a11548a3..d6d36b0d 100644
--- a/asset/js/widget/Completer.js
+++ b/asset/js/widget/Completer.js
@@ -695,18 +695,6 @@ define(["../notjQuery"], function ($) {
                         event.preventDefault();
                         this.moveToSuggestion();
                     }
-
-                    break;
-                default:
-                    if (/[A-Z]/.test(event.key.charAt(0)) || event.key === '"') {
-                        // Ignore control keys not resulting in new input data
-                        break;
-                    }
-
-                    let typedSuggestion = this.termSuggestions.querySelector(`[value="${ event.key }"]`);
-                    if (typedSuggestion !== null) {
-                        this.hideSuggestions();
-                    }
             }
         }
 
diff --git a/asset/js/widget/FilterInput.js b/asset/js/widget/FilterInput.js
index 3f1d9478..51cb0f78 100644
--- a/asset/js/widget/FilterInput.js
+++ b/asset/js/widget/FilterInput.js
@@ -1,4 +1,4 @@
-define(["../notjQuery", "BaseInput"], function ($, BaseInput) {
+define(["../notjQuery", "../functions", "BaseInput"], function ($, functions, BaseInput) {
 
     "use strict";
 
@@ -1350,7 +1350,7 @@ define(["../notjQuery", "BaseInput"], function ($, BaseInput) {
             } else if (input.selectionStart !== input.selectionEnd) {
                 // In case the user selected a range of text, do nothing
                 return;
-            } else if (/[A-Z]/.test(event.key.charAt(0)) || event.ctrlKey || event.metaKey) {
+            } else if (functions.isSpecialKeyPress(event)) {
                 // Ignore control keys not resulting in new input data
                 // TODO: Remove this and move the entire block into `onInput`
                 //       once Safari supports `InputEvent.data`