Close list dropdown when clicking outside of it

app/modifiers/on-click-outside.js

@@ -0,0 +1,21 @@
+import { modifier } from 'ember-modifier';
+
+export default modifier((element, [callback]) => {
+  const handler = (event) => {
+    // Check if the click target is contained within the element
+    if (element && !element.contains(event.target)) {
+      callback(event);
+    }
+  };
+
+  // Delay attaching the listener to avoid catching the opening click
+  // (using a microtask or setTimeout 0)
+  const timer = setTimeout(() => {
+    document.addEventListener('click', handler);
+  }, 0);
+
+  return () => {
+    clearTimeout(timer);
+    document.removeEventListener('click', handler);
+  };
+});