From ae724be7becd26f924b3888959b3e84b78a7e34d Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Wed, 11 Sep 2019 12:46:41 +0200
Subject: [PATCH] [react-interactions] Add TabFocusContainer and TabbableScope
 UI components (#16732)

---
 .../src/client/focus/TabFocusContainer.js     |  81 +++++++
 .../src/client/focus/TabbableScope.js         |  35 +++
 .../TabFocusContainer-test.internal.js        | 225 ++++++++++++++++++
 .../__tests__/TabbableScope-test.internal.js  |  73 ++++++
 packages/react-events/src/dom/Keyboard.js     |  14 +-
 .../src/dom/testing-library/index.js          |  26 ++
 .../src/ReactFiberCommitWork.js               |   6 +
 .../src/__tests__/ReactScope-test.internal.js |   2 +
 8 files changed, 455 insertions(+), 7 deletions(-)
 create mode 100644 packages/react-dom/src/client/focus/TabFocusContainer.js
 create mode 100644 packages/react-dom/src/client/focus/TabbableScope.js
 create mode 100644 packages/react-dom/src/client/focus/__tests__/TabFocusContainer-test.internal.js
 create mode 100644 packages/react-dom/src/client/focus/__tests__/TabbableScope-test.internal.js

diff --git a/packages/react-dom/src/client/focus/TabFocusContainer.js b/packages/react-dom/src/client/focus/TabFocusContainer.js
new file mode 100644
index 000000000000..b6d930f84048
--- /dev/null
+++ b/packages/react-dom/src/client/focus/TabFocusContainer.js
@@ -0,0 +1,81 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import React from 'react';
+import {TabbableScope} from './TabbableScope';
+import {useKeyboard} from 'react-events/keyboard';
+
+type TabFocusContainerProps = {
+  children: React.Node,
+};
+
+type KeyboardEventType = 'keydown' | 'keyup';
+
+type KeyboardEvent = {|
+  altKey: boolean,
+  ctrlKey: boolean,
+  isComposing: boolean,
+  key: string,
+  location: number,
+  metaKey: boolean,
+  repeat: boolean,
+  shiftKey: boolean,
+  target: Element | Document,
+  type: KeyboardEventType,
+  timeStamp: number,
+  defaultPrevented: boolean,
+|};
+
+const {useRef} = React;
+
+export function TabFocusContainer({
+  children,
+}: TabFocusContainerProps): React.Node {
+  const scopeRef = useRef(null);
+  const keyboard = useKeyboard({onKeyDown, preventKeys: ['tab']});
+
+  function onKeyDown(event: KeyboardEvent): boolean {
+    if (event.key !== 'Tab') {
+      return true;
+    }
+    const tabbableScope = scopeRef.current;
+    const tabbableNodes = tabbableScope.getScopedNodes();
+    const currentIndex = tabbableNodes.indexOf(document.activeElement);
+    const firstTabbableElem = tabbableNodes[0];
+    const lastTabbableElem = tabbableNodes[tabbableNodes.length - 1];
+
+    // We want to wrap focus back to start/end depending if
+    // shift is pressed when tabbing.
+    if (currentIndex === -1) {
+      firstTabbableElem.focus();
+    } else {
+      const focusedElement = tabbableNodes[currentIndex];
+      if (event.shiftKey) {
+        if (focusedElement === firstTabbableElem) {
+          lastTabbableElem.focus();
+        } else {
+          tabbableNodes[currentIndex - 1].focus();
+        }
+      } else {
+        if (focusedElement === lastTabbableElem) {
+          firstTabbableElem.focus();
+        } else {
+          tabbableNodes[currentIndex + 1].focus();
+        }
+      }
+    }
+    return false;
+  }
+
+  return (
+    <TabbableScope ref={scopeRef} listeners={keyboard}>
+      {children}
+    </TabbableScope>
+  );
+}
diff --git a/packages/react-dom/src/client/focus/TabbableScope.js b/packages/react-dom/src/client/focus/TabbableScope.js
new file mode 100644
index 000000000000..57b86d528681
--- /dev/null
+++ b/packages/react-dom/src/client/focus/TabbableScope.js
@@ -0,0 +1,35 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import React from 'react';
+
+export const TabbableScope = React.unstable_createScope(
+  (type: string, props: Object): boolean => {
+    if (props.tabIndex === -1 || props.disabled) {
+      return false;
+    }
+    if (props.tabIndex === 0 || props.contentEditable === true) {
+      return true;
+    }
+    if (type === 'a' || type === 'area') {
+      return !!props.href && props.rel !== 'ignore';
+    }
+    if (type === 'input') {
+      return props.type !== 'hidden' && props.type !== 'file';
+    }
+    return (
+      type === 'button' ||
+      type === 'textarea' ||
+      type === 'object' ||
+      type === 'select' ||
+      type === 'iframe' ||
+      type === 'embed'
+    );
+  },
+);
diff --git a/packages/react-dom/src/client/focus/__tests__/TabFocusContainer-test.internal.js b/packages/react-dom/src/client/focus/__tests__/TabFocusContainer-test.internal.js
new file mode 100644
index 000000000000..4f1872d6e225
--- /dev/null
+++ b/packages/react-dom/src/client/focus/__tests__/TabFocusContainer-test.internal.js
@@ -0,0 +1,225 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import {createEventTarget} from 'react-events/src/dom/testing-library';
+
+let React;
+let ReactFeatureFlags;
+let TabFocusContainer;
+
+describe('TabFocusContainer', () => {
+  beforeEach(() => {
+    jest.resetModules();
+    ReactFeatureFlags = require('shared/ReactFeatureFlags');
+    ReactFeatureFlags.enableScopeAPI = true;
+    ReactFeatureFlags.enableFlareAPI = true;
+    TabFocusContainer = require('../TabFocusContainer').TabFocusContainer;
+    React = require('react');
+  });
+
+  describe('ReactDOM', () => {
+    let ReactDOM;
+    let container;
+
+    beforeEach(() => {
+      ReactDOM = require('react-dom');
+      container = document.createElement('div');
+      document.body.appendChild(container);
+    });
+
+    afterEach(() => {
+      document.body.removeChild(container);
+      container = null;
+    });
+
+    it('should work as expected with simple tab operations', () => {
+      const inputRef = React.createRef();
+      const input2Ref = React.createRef();
+      const buttonRef = React.createRef();
+      const butto2nRef = React.createRef();
+      const divRef = React.createRef();
+
+      const Test = () => (
+        <TabFocusContainer>
+          <input ref={inputRef} />
+          <button ref={buttonRef} />
+          <div ref={divRef} tabIndex={0} />
+          <input ref={input2Ref} tabIndex={-1} />
+          <button ref={butto2nRef} />
+        </TabFocusContainer>
+      );
+
+      ReactDOM.render(<Test />, container);
+      inputRef.current.focus();
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(buttonRef.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(divRef.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(butto2nRef.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(divRef.current);
+    });
+
+    it('should work as expected with wrapping tab operations', () => {
+      const inputRef = React.createRef();
+      const input2Ref = React.createRef();
+      const buttonRef = React.createRef();
+      const button2Ref = React.createRef();
+
+      const Test = () => (
+        <TabFocusContainer>
+          <input ref={inputRef} tabIndex={-1} />
+          <button ref={buttonRef} id={1} />
+          <button ref={button2Ref} id={2} />
+          <input ref={input2Ref} tabIndex={-1} />
+        </TabFocusContainer>
+      );
+
+      ReactDOM.render(<Test />, container);
+      buttonRef.current.focus();
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button2Ref.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(buttonRef.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button2Ref.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(buttonRef.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button2Ref.current);
+    });
+
+    it('should work as expected when nested', () => {
+      const inputRef = React.createRef();
+      const input2Ref = React.createRef();
+      const buttonRef = React.createRef();
+      const button2Ref = React.createRef();
+      const button3Ref = React.createRef();
+      const button4Ref = React.createRef();
+
+      const Test = () => (
+        <TabFocusContainer>
+          <input ref={inputRef} tabIndex={-1} />
+          <button ref={buttonRef} id={1} />
+          <TabFocusContainer>
+            <button ref={button2Ref} id={2} />
+            <button ref={button3Ref} id={3} />
+          </TabFocusContainer>
+          <input ref={input2Ref} tabIndex={-1} />
+          <button ref={button4Ref} id={4} />
+        </TabFocusContainer>
+      );
+
+      ReactDOM.render(<Test />, container);
+      buttonRef.current.focus();
+      expect(document.activeElement).toBe(buttonRef.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button2Ref.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button3Ref.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button2Ref.current);
+      // Focus is contained, so have to manually move it out
+      button4Ref.current.focus();
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(buttonRef.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button4Ref.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button3Ref.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button2Ref.current);
+    });
+
+    it('should work as expected when nested with scope that is contained', () => {
+      const inputRef = React.createRef();
+      const input2Ref = React.createRef();
+      const buttonRef = React.createRef();
+      const button2Ref = React.createRef();
+      const button3Ref = React.createRef();
+      const button4Ref = React.createRef();
+
+      const Test = () => (
+        <TabFocusContainer>
+          <input ref={inputRef} tabIndex={-1} />
+          <button ref={buttonRef} id={1} />
+          <TabFocusContainer>
+            <button ref={button2Ref} id={2} />
+            <button ref={button3Ref} id={3} />
+          </TabFocusContainer>
+          <input ref={input2Ref} tabIndex={-1} />
+          <button ref={button4Ref} id={4} />
+        </TabFocusContainer>
+      );
+
+      ReactDOM.render(<Test />, container);
+      buttonRef.current.focus();
+      expect(document.activeElement).toBe(buttonRef.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button2Ref.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button3Ref.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button2Ref.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button3Ref.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button2Ref.current);
+    });
+
+    it('should work as expected with suspense fallbacks', () => {
+      const buttonRef = React.createRef();
+      const button2Ref = React.createRef();
+      const button3Ref = React.createRef();
+      const button4Ref = React.createRef();
+      const button5Ref = React.createRef();
+
+      function SuspendedComponent() {
+        throw new Promise(() => {
+          // Never resolve
+        });
+      }
+
+      function Component() {
+        return (
+          <React.Fragment>
+            <button ref={button5Ref} id={5} />
+            <SuspendedComponent />
+          </React.Fragment>
+        );
+      }
+
+      const Test = () => (
+        <TabFocusContainer>
+          <button ref={buttonRef} id={1} />
+          <button ref={button2Ref} id={2} />
+          <React.Suspense fallback={<button ref={button3Ref} id={3} />}>
+            <Component />
+          </React.Suspense>
+          <button ref={button4Ref} id={4} />
+        </TabFocusContainer>
+      );
+
+      ReactDOM.render(<Test />, container);
+      buttonRef.current.focus();
+      expect(document.activeElement).toBe(buttonRef.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button2Ref.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button3Ref.current);
+      createEventTarget(document.activeElement).tabNext();
+      expect(document.activeElement).toBe(button4Ref.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button3Ref.current);
+      createEventTarget(document.activeElement).tabPrevious();
+      expect(document.activeElement).toBe(button2Ref.current);
+    });
+  });
+});
diff --git a/packages/react-dom/src/client/focus/__tests__/TabbableScope-test.internal.js b/packages/react-dom/src/client/focus/__tests__/TabbableScope-test.internal.js
new file mode 100644
index 000000000000..4f5aa0916160
--- /dev/null
+++ b/packages/react-dom/src/client/focus/__tests__/TabbableScope-test.internal.js
@@ -0,0 +1,73 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+let React;
+let ReactFeatureFlags;
+let TabbableScope;
+
+describe('TabbableScope', () => {
+  beforeEach(() => {
+    jest.resetModules();
+    ReactFeatureFlags = require('shared/ReactFeatureFlags');
+    ReactFeatureFlags.enableScopeAPI = true;
+    TabbableScope = require('../TabbableScope').TabbableScope;
+    React = require('react');
+  });
+
+  describe('ReactDOM', () => {
+    let ReactDOM;
+    let container;
+
+    beforeEach(() => {
+      ReactDOM = require('react-dom');
+      container = document.createElement('div');
+      document.body.appendChild(container);
+    });
+
+    afterEach(() => {
+      document.body.removeChild(container);
+      container = null;
+    });
+
+    it('getScopedNodes() works as intended', () => {
+      const scopeRef = React.createRef();
+      const nodeRefA = React.createRef();
+      const nodeRefB = React.createRef();
+      const nodeRefC = React.createRef();
+      const nodeRefD = React.createRef();
+
+      function Test() {
+        return (
+          <TabbableScope ref={scopeRef}>
+            <input ref={nodeRefA} />
+            <textarea ref={nodeRefB} />
+            <div tabIndex={0} ref={nodeRefC}>
+              <input tabIndex={-1} />
+              <div tabIndex={0} ref={nodeRefD} />
+            </div>
+            <input disabled={true} />
+            <div tabIndex={-1} />
+          </TabbableScope>
+        );
+      }
+
+      ReactDOM.render(<Test />, container);
+      let nodes = scopeRef.current.getScopedNodes();
+      expect(nodes).toEqual([
+        nodeRefA.current,
+        nodeRefB.current,
+        nodeRefC.current,
+        nodeRefD.current,
+      ]);
+      expect(nodes.length).toBe(4);
+      ReactDOM.render(null, container);
+      expect(scopeRef.current).toBe(null);
+    });
+  });
+});
diff --git a/packages/react-events/src/dom/Keyboard.js b/packages/react-events/src/dom/Keyboard.js
index ad9bbde916ab..a41dbe8886e2 100644
--- a/packages/react-events/src/dom/Keyboard.js
+++ b/packages/react-events/src/dom/Keyboard.js
@@ -19,10 +19,10 @@ import type {ReactEventResponderListener} from 'shared/ReactTypes';
 type KeyboardEventType = 'keydown' | 'keyup';
 
 type KeyboardProps = {
-  disabled: boolean,
-  onKeyDown: (e: KeyboardEvent) => ?boolean,
-  onKeyUp: (e: KeyboardEvent) => ?boolean,
-  preventKeys: Array<string>,
+  disabled?: boolean,
+  onKeyDown?: (e: KeyboardEvent) => ?boolean,
+  onKeyUp?: (e: KeyboardEvent) => ?boolean,
+  preventKeys?: Array<string>,
 };
 
 type KeyboardEvent = {|
@@ -198,7 +198,7 @@ const keyboardResponderImpl = {
     }
     let defaultPrevented = nativeEvent.defaultPrevented === true;
     if (type === 'keydown') {
-      const preventKeys = props.preventKeys;
+      const preventKeys = ((props.preventKeys: any): Array<string>);
       if (!defaultPrevented && isArray(preventKeys)) {
         preventKeyLoop: for (let i = 0; i < preventKeys.length; i++) {
           const preventKey = preventKeys[i];
@@ -230,7 +230,7 @@ const keyboardResponderImpl = {
       if (isFunction(onKeyDown)) {
         dispatchKeyboardEvent(
           event,
-          onKeyDown,
+          ((onKeyDown: any): (e: KeyboardEvent) => ?boolean),
           context,
           'keydown',
           defaultPrevented,
@@ -241,7 +241,7 @@ const keyboardResponderImpl = {
       if (isFunction(onKeyUp)) {
         dispatchKeyboardEvent(
           event,
-          onKeyUp,
+          ((onKeyUp: any): (e: KeyboardEvent) => ?boolean),
           context,
           'keyup',
           defaultPrevented,
diff --git a/packages/react-events/src/dom/testing-library/index.js b/packages/react-events/src/dom/testing-library/index.js
index 40fb6beb80a0..d46f96a5058c 100644
--- a/packages/react-events/src/dom/testing-library/index.js
+++ b/packages/react-events/src/dom/testing-library/index.js
@@ -50,6 +50,32 @@ const createEventTarget = node => ({
   virtualclick(payload) {
     node.dispatchEvent(domEvents.virtualclick(payload));
   },
+  tabNext() {
+    node.dispatchEvent(
+      domEvents.keydown({
+        key: 'Tab',
+      }),
+    );
+    node.dispatchEvent(
+      domEvents.keyup({
+        key: 'Tab',
+      }),
+    );
+  },
+  tabPrevious() {
+    node.dispatchEvent(
+      domEvents.keydown({
+        key: 'Tab',
+        shiftKey: true,
+      }),
+    );
+    node.dispatchEvent(
+      domEvents.keyup({
+        key: 'Tab',
+        shiftKey: true,
+      }),
+    );
+  },
   /**
    * PointerEvent abstraction.
    * Dispatches the expected sequence of PointerEvents, MouseEvents, and
diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.js b/packages/react-reconciler/src/ReactFiberCommitWork.js
index 6a59ce860727..ffce3166eb40 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.js
@@ -843,6 +843,12 @@ function commitUnmount(
           }
         }
       }
+      return;
+    }
+    case ScopeComponent: {
+      if (enableScopeAPI) {
+        safelyDetachRef(current);
+      }
     }
   }
 }
diff --git a/packages/react-reconciler/src/__tests__/ReactScope-test.internal.js b/packages/react-reconciler/src/__tests__/ReactScope-test.internal.js
index 9ceca7f77268..b55422c3d531 100644
--- a/packages/react-reconciler/src/__tests__/ReactScope-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactScope-test.internal.js
@@ -67,6 +67,8 @@ describe('ReactScope', () => {
       ReactDOM.render(<Test toggle={false} />, container);
       nodes = scopeRef.current.getScopedNodes();
       expect(nodes).toEqual([aRef.current, divRef.current, spanRef.current]);
+      ReactDOM.render(null, container);
+      expect(scopeRef.current).toBe(null);
     });
 
     it('mixed getParent() and getScopedNodes() works as intended', () => {