reset active element/focus order state on ui close (#158)

* reset active element/focus order state on ui close

src/components/App.tsx

@@ -58,6 +58,11 @@ export function App({
       initialViewState,
       dismissedViewState,
       eventTarget,
+      savedActiveElement:
+        document.activeElement instanceof HTMLElement &&
+        document.activeElement !== document.body
+          ? document.activeElement
+          : null,
     });
 
   // Language setup

src/hooks/useViewState.ts

@@ -52,13 +52,16 @@ export function useViewState({
   initialViewState,
   dismissedViewState,
   eventTarget,
+  savedActiveElement,
 }: {
   /** Which state this consent manager should go to when opened */
   initialViewState: InitialViewState;
   /** Which state this consent manager should go to when closed */
   dismissedViewState: DismissedViewState;
   /** The event target on the `transcend` API, where we will dispatch view state change events */
   eventTarget: EventTarget;
+  /** Element previously focused before our ui modal was opened */
+  savedActiveElement: HTMLElement | null;
 }): {
   /** The current view state */
   viewState: ViewState;
@@ -118,14 +121,30 @@ export function useViewState({
           break;
 
         // Request to close the modal, to the closed view state (which depends on whether customer wants to display the collapse view or hide it)
-        case 'close':
+        case 'close': {
           setState({
             current: dismissedViewState,
             previous: state.current,
             auth,
             firstSelectedViewState: null,
           });
+          /* If the user previously had something focused before the modal popped up, then focus it.
+           * Otherwise, we have to do this really janky "reset" behavior with the temporary element
+           * because Chrome specifically has some weird internal state around focus order that is
+           * very difficult to interact with. We create an element with maximum focus priority and
+           * focus it so that when we delete it the user will be at the start of the focus order
+           * just like if they had freshly loaded the page. */
+          if (savedActiveElement !== null) {
+            savedActiveElement.focus();
+          } else {
+            const tempInteractiveEl = document.createElement('span');
+            tempInteractiveEl.setAttribute('tabindex', '1');
+            document.body.prepend(tempInteractiveEl);
+            tempInteractiveEl.focus();
+            tempInteractiveEl.remove();
+          }
           break;
+        }
 
         // Request to go to a specific view state, e.g. the language options page
         default: