Display notebook in a native dialog when possible

src/annotator/components/NotebookModal.tsx

 import { IconButton, CancelIcon } from '@hypothesis/frontend-shared';
 import classnames from 'classnames';
-import { useEffect, useRef, useState } from 'preact/hooks';
+import type { ComponentChildren } from 'preact';
+import { useEffect, useMemo, useRef, useState } from 'preact/hooks';
 
 import { addConfigFragment } from '../../shared/config-fragment';
 import { createAppConfig } from '../config/app';
@@ -27,7 +28,7 @@ function NotebookIframe({ config, groupId }: NotebookIframeProps) {
   const notebookAppSrc = addConfigFragment(config.notebookAppUrl, {
     ...createAppConfig(config.notebookAppUrl, config),
 
-    // Explicity set the "focused" group
+    // Explicitly set the "focused" group
     group: groupId,
   });
 
@@ -40,9 +41,76 @@ function NotebookIframe({ config, groupId }: NotebookIframeProps) {
     />
   );
 }
+
+/** Checks if the browser supports native modal dialogs */
+function isModalDialogSupported(document: Document) {
+  const dialog = document.createElement('dialog');
+  return typeof dialog.showModal === 'function';
+}
+
 export type NotebookModalProps = {
   eventBus: EventBus;
   config: NotebookConfig;
+
+  /** Test seam */
+  document_?: Document;
+};
+
+type DialogProps = { isHidden: boolean; children: ComponentChildren };
+
+const NativeDialog = ({ isHidden, children }: DialogProps) => {
+  const dialogRef = useRef<HTMLDialogElement | null>(null);
+
+  useEffect(() => {
+    if (isHidden) {
+      dialogRef.current?.close();
+    } else {
+      dialogRef.current?.showModal();
+    }
+  }, [isHidden]);
+
+  // Prevent the dialog from closing when `Esc` is pressed, to keep previous
+  // behavior
+  useEffect(() => {
+    const dialogElement = dialogRef.current;
+    const listener = (event: Event) => event.preventDefault();
+
+    dialogElement?.addEventListener('cancel', listener);
+
+    return () => {
+      dialogElement?.removeEventListener('cancel', listener);
+    };
+  }, []);
+
+  return (
+    <dialog
+      ref={dialogRef}
+      className="relative w-full h-full backdrop:bg-black/50"
+      data-testid="notebook-outer"
+    >
+      {children}
+    </dialog>
+  );
+};
+
+/**
+ * Temporary fallback used in browsers not supporting `dialog` element.
+ * It can be removed once all browsers we support can use it.
+ */
+const FallbackDialog = ({ isHidden, children }: DialogProps) => {
+  return (
+    <div
+      className={classnames(
+        'fixed z-max top-0 left-0 right-0 bottom-0 p-3 bg-black/50',
+        { hidden: isHidden },
+      )}
+      data-testid="notebook-outer"
+    >
+      <div className="relative w-full h-full" data-testid="notebook-inner">
+        {children}
+      </div>
+    </div>
+  );
 };
 
 /**
@@ -51,6 +119,8 @@ export type NotebookModalProps = {
 export default function NotebookModal({
   eventBus,
   config,
+  /* istanbul ignore next - test seam */
+  document_ = document,
 }: NotebookModalProps) {
   // Temporary solution: while there is no mechanism to sync new annotations in
   // the notebook, we force re-rendering of the iframe on every 'openNotebook'
@@ -62,6 +132,11 @@ export default function NotebookModal({
   const originalDocumentOverflowStyle = useRef('');
   const emitterRef = useRef<Emitter | null>(null);
 
+  const Dialog = useMemo(
+    () => (isModalDialogSupported(document_) ? NativeDialog : FallbackDialog),
+    [document_],
+  );
+
   // Stores the original overflow CSS property of document.body and reset it
   // when the component is destroyed
   useEffect(() => {
@@ -106,14 +181,7 @@ export default function NotebookModal({
   }
 
   return (
-    <div
-      className={classnames(
-        'fixed z-max top-0 left-0 right-0 bottom-0 p-3 bg-black/50',
-        { hidden: isHidden },
-      )}
-      data-testid="notebook-outer"
-    >
-      <div className="relative w-full h-full" data-testid="notebook-inner">
+    <Dialog isHidden={isHidden}>
       <div className="absolute right-0 m-3">
         <IconButton
           title="Close the Notebook"
@@ -126,12 +194,12 @@ export default function NotebookModal({
             // See https://github.com/hypothesis/client/issues/3676
             '!bg-transparent enabled:hover:!bg-grey-3',
           )}
+          data-testid="close-button"
         >
           <CancelIcon className="w-4 h-4" />
         </IconButton>
       </div>
       <NotebookIframe key={iframeKey} config={config} groupId={groupId} />
-      </div>
-    </div>
+    </Dialog>
   );
 }

src/annotator/components/test/NotebookModal-test.js

@@ -14,14 +14,19 @@ describe('NotebookModal', () => {
 
   const outerSelector = '[data-testid="notebook-outer"]';
 
-  const createComponent = config => {
+  const createComponent = (config, fakeDocument) => {
+    const attachTo = document.createElement('div');
+    document.body.appendChild(attachTo);
+
     const component = mount(
       <NotebookModal
         eventBus={eventBus}
         config={{ notebookAppUrl: notebookURL, ...config }}
+        document_={fakeDocument}
       />,
+      { attachTo },
     );
-    components.push(component);
+    components.push([component, attachTo]);
     return component;
   };
 
@@ -42,10 +47,16 @@ describe('NotebookModal', () => {
   });
 
   afterEach(() => {
-    components.forEach(component => component.unmount());
+    components.forEach(([component, container]) => {
+      component.unmount();
+      container.remove();
+    });
     $imports.$restore();
   });
 
+  const getCloseButton = wrapper =>
+    wrapper.find('IconButton[data-testid="close-button"]');
+
   it('hides modal on first render', () => {
     const wrapper = createComponent();
     const outer = wrapper.find(outerSelector);
@@ -114,8 +125,26 @@ describe('NotebookModal', () => {
     assert.equal(document.body.style.overflow, 'hidden');
   });
 
+  context('when native modal dialog is not supported', () => {
+    let fakeDocument;
+
+    beforeEach(() => {
+      fakeDocument = {
+        createElement: sinon.stub().returns({}),
+      };
+    });
+
+    it('does not render a dialog element', () => {
+      const wrapper = createComponent({}, fakeDocument);
+
+      emitter.publish('openNotebook', 'myGroup');
+      wrapper.update();
+
+      assert.isFalse(wrapper.exists('dialog'));
+    });
+
     it('hides modal on closing', () => {
-    const wrapper = createComponent();
+      const wrapper = createComponent({}, fakeDocument);
 
       emitter.publish('openNotebook', 'myGroup');
       wrapper.update();
@@ -124,7 +153,7 @@ describe('NotebookModal', () => {
       assert.isFalse(outer.hasClass('hidden'));
 
       act(() => {
-      wrapper.find('IconButton').prop('onClick')();
+        getCloseButton(wrapper).prop('onClick')();
       });
       wrapper.update();
 
@@ -132,6 +161,31 @@ describe('NotebookModal', () => {
 
       assert.isTrue(outer.hasClass('hidden'));
     });
+  });
+
+  context('when native modal dialog is supported', () => {
+    it('renders a dialog element', () => {
+      const wrapper = createComponent({});
+
+      emitter.publish('openNotebook', 'myGroup');
+      wrapper.update();
+
+      assert.isTrue(wrapper.exists('dialog'));
+    });
+
+    it('opens and closes native dialog', () => {
+      const wrapper = createComponent({});
+      const isDialogOpen = () => wrapper.find('dialog').getDOMNode().open;
+
+      act(() => emitter.publish('openNotebook', 'myGroup'));
+      wrapper.update();
+      assert.isTrue(isDialogOpen());
+
+      act(() => getCloseButton(wrapper).prop('onClick')());
+      wrapper.update();
+      assert.isFalse(isDialogOpen());
+    });
+  });
 
   it('resets document scrollability on closing the modal', () => {
     const wrapper = createComponent();
@@ -141,7 +195,7 @@ describe('NotebookModal', () => {
     assert.equal(document.body.style.overflow, 'hidden');
     wrapper.update();
     act(() => {
-      wrapper.find('IconButton').prop('onClick')();
+      getCloseButton(wrapper).prop('onClick')();
     });
     assert.notEqual(document.body.style.overflow, 'hidden');
   });