fix: auto-focus in case of activeElement disappearance, fixes #321

.size-limit.json

@@ -1,7 +1,7 @@
 [
   {
     "path": "dist/cjs/UI.js",
-    "limit": "3.8 KB",
+    "limit": "3.9 KB",
     "ignore": [
       "prop-types",
       "@babel/runtime",
@@ -10,7 +10,7 @@
   },
   {
     "path": "dist/es2015/sidecar.js",
-    "limit": "4.6 KB",
+    "limit": "4.85 KB",
     "ignore": [
       "prop-types",
       "@babel/runtime",
@@ -19,7 +19,7 @@
   },
   {
     "path": "dist/es2015/index.js",
-    "limit": "6.9 KB",
+    "limit": "7.2 KB",
     "ignore": [
       "prop-types",
       "@babel/runtime",

_tests/keep-focus.spec.js

@@ -1,20 +1,102 @@
 import React from 'react';
 import {
-  render, screen,
+  render,
 } from '@testing-library/react';
 import { expect } from 'chai';
 import FocusLock from '../src';
+import { deferAction } from '../src/util';
 
-describe('Focus restoration', () => {
+describe('Focus restoration', async () => {
   it('maintains focus on element removal', async () => {
+    const { rerender } = render(
+      <FocusLock>
+        <button type="button" key={1}>btn1</button>
+      </FocusLock>,
+    );
+    //
+    expect(document.activeElement.innerHTML).to.be.equal('btn1');
+
+    rerender(
+      <FocusLock>
+        <button type="button" key={2}>new button</button>
+      </FocusLock>,
+    );
+
+    // wait
+    await new Promise(deferAction);
+
+    expect(document.activeElement.innerHTML).to.be.equal('new button');
+  });
+
+  it('handles disabled elements', async () => {
+    const { rerender } = render(
+      <FocusLock>
+        <button type="button">btn1</button>
+        <button type="button">btn2</button>
+      </FocusLock>,
+    );
+    //
+    expect(document.activeElement.innerHTML).to.be.equal('btn1');
+
+
+    // https://github.com/jsdom/jsdom/issues/3029 - jsdom does trigger blur on disabled
+    document.activeElement.blur();
+    document.body.focus();
+
+    rerender(
+      <FocusLock>
+        <button type="button" disabled>btn1</button>
+        <button type="button">btn2</button>
+      </FocusLock>,
+    );
+
+    // wait
+    await new Promise(deferAction);
+
+    expect(document.activeElement.innerHTML).to.be.equal('btn2');
+  });
+
+  it('moves focus to the nearest element', async () => {
     render(
       <FocusLock>
-        <button type="button">test</button>
+        <button type="button">btn1</button>
+        <button type="button">btn2</button>
+        <button type="button" id="middle-button">btn3</button>
+        <button type="button">btn4</button>
+        <button type="button">btn5</button>
       </FocusLock>,
     );
     //
-    expect(document.activeElement).to.be.equal(screen.getByRole('button'));
+    const middleButton = document.getElementById('middle-button');
+    middleButton.focus();
+    expect(document.activeElement).to.be.equal(middleButton);
+
+    middleButton.parentElement.removeChild(middleButton);
+    // wait
+    await new Promise(deferAction);
+
+    // btn4 "replaces" bnt3 in visual order
+    expect(document.activeElement.innerHTML).to.be.equal('btn4');
   });
 
-  it.todo('selects closes element to restore focus');
+  it('moves focus to the nearest element before', async () => {
+    render(
+      <FocusLock>
+        <button type="button">btn1</button>
+        <button type="button">btn2</button>
+        <button type="button" id="middle-button">btn3</button>
+      </FocusLock>,
+    );
+    //
+    const middleButton = document.getElementById('middle-button');
+    middleButton.focus();
+    expect(document.activeElement).to.be.equal(middleButton);
+
+    middleButton.parentElement.removeChild(middleButton);
+    // wait
+    await new Promise(deferAction);
+
+    // btn2 is just before bnt3
+    expect(document.activeElement.innerHTML).to.be.equal('btn2');
+  });
 });

src/Lock.js

@@ -173,6 +173,7 @@ const FocusLock = React.forwardRef(function FocusLockUI(props, parentRef) {
           onDeactivation={onDeactivation}
           returnFocus={returnFocus}
           focusOptions={focusOptions}
+          noFocusGuards={noFocusGuards}
         />
       )}
       <Container

src/Trap.js

@@ -4,7 +4,9 @@ import PropTypes from 'prop-types';
 import withSideEffect from 'react-clientside-effect';
 import {
   moveFocusInside, focusInside,
-  focusIsHidden, expandFocusableNodes,
+  focusIsHidden,
+  expandFocusableNodes,
+  getFocusableNodes,
   focusNextElement,
   focusPrevElement,
   focusFirstElement,
@@ -22,10 +24,12 @@ const isFreeFocus = () => focusOnBody() || focusIsHidden();
 
 let lastActiveTrap = null;
 let lastActiveFocus = null;
+let tryRestoreFocus = () => null;
 
 let lastPortaledElement = null;
 
 let focusWasOutsideWindow = false;
+let windowFocused = false;
 
 const defaultWhitelist = () => true;
 
@@ -86,23 +90,61 @@ const withinHost = (activeElement, workingArea) => (
   workingArea.some(area => checkInHost(activeElement, area, area))
 );
 
+const getNodeFocusables = nodes => getFocusableNodes(nodes, new Map());
+const isNotFocusable = node => (
+  !getNodeFocusables([node.parentNode]).some(el => el.node === node)
+);
+
 const activateTrap = () => {
   let result = false;
   if (lastActiveTrap) {
     const {
-      observed, persistentFocus, autoFocus, shards, crossFrame, focusOptions,
+      observed, persistentFocus, autoFocus, shards, crossFrame, focusOptions, noFocusGuards,
     } = lastActiveTrap;
     const workingNode = observed || (lastPortaledElement && lastPortaledElement.portaledElement);
+
+    // check if lastActiveFocus is still reachable
+    if (focusOnBody() && lastActiveFocus) {
+      if (
+        // it was removed
+        !document.body.contains(lastActiveFocus)
+          // or not focusable (this is expensive operation)!
+          || isNotFocusable(lastActiveFocus)
+      ) {
+        lastActiveFocus = null;
+
+        const newTarget = tryRestoreFocus();
+        if (newTarget) {
+          newTarget.focus();
+        }
+      }
+    }
+
     const activeElement = document && document.activeElement;
     if (workingNode) {
       const workingArea = [
         workingNode,
         ...shards.map(extractRef).filter(Boolean),
       ];
 
+      const shouldForceRestoreFocus = () => {
+        // force restoration happens when
+        // - focus is not inside now
+        // - focusWasOutside
+        // - there are go guards
+        // - the last active element was the first or the last focusable one
+        if (!focusWasOutside(crossFrame) || !noFocusGuards || !lastActiveFocus || windowFocused) {
+          return false;
+        }
+        const nodes = getNodeFocusables(workingArea);
+        const lastIndex = nodes.findIndex(({ node }) => node === lastActiveFocus);
+
+        return lastIndex === 0 || lastIndex === nodes.length - 1;
+      };
+
       if (!activeElement || focusWhitelisted(activeElement)) {
         if (
-          (persistentFocus || focusWasOutside(crossFrame))
+          (persistentFocus || shouldForceRestoreFocus())
           || !isFreeFocus()
           || (!lastActiveFocus && autoFocus)
         ) {
@@ -130,11 +172,12 @@ const activateTrap = () => {
           }
           focusWasOutsideWindow = false;
           lastActiveFocus = document && document.activeElement;
+          tryRestoreFocus = captureFocusRestore(lastActiveFocus);
         }
       }
 
       if (document
-          // element was changed
+          // element was changed by moveFocusInside
           && activeElement !== document.activeElement
           // fast check for any auto-guard
           && document.querySelector('[data-focus-auto-guard]')) {
@@ -189,7 +232,11 @@ FocusTrap.propTypes = {
   children: PropTypes.node.isRequired,
 };
 
+const onWindowFocus = () => {
+  windowFocused = true;
+};
 const onWindowBlur = () => {
+  windowFocused = false;
   focusWasOutsideWindow = 'just';
   // using setTimeout to set  this variable after React/sidecar reaction
   deferAction(() => {
@@ -200,12 +247,14 @@ const onWindowBlur = () => {
 const attachHandler = () => {
   document.addEventListener('focusin', onTrap);
   document.addEventListener('focusout', onBlur);
+  window.addEventListener('focus', onWindowFocus);
   window.addEventListener('blur', onWindowBlur);
 };
 
 const detachHandler = () => {
   document.removeEventListener('focusin', onTrap);
   document.removeEventListener('focusout', onBlur);
+  window.removeEventListener('focus', onWindowFocus);
   window.removeEventListener('blur', onWindowBlur);
 };
 

stories/Iframe.js

@@ -74,9 +74,23 @@ export const IFrame = props => (
       {' '}
       outside
     </div>
+    <hr />
+    <Trap {...props} />
+    <hr />
+
     <Trap {...props}>
-      <iframe src={`/iframe.html?id=focus-lock--codesandbox-example&crossFrame=${props.crossFrame}`} style={{ width: '100%', height: '400px' }} />
+      <iframe
+        src={`/iframe.html?id=focus-lock--codesandbox-example&crossFrame=${props.crossFrame}`}
+        style={{ width: '100%', height: '400px' }}
+      />
+      <iframe
+        src={`/iframe.html?id=focus-lock--codesandbox-example&crossFrame=${props.crossFrame}`}
+        style={{ width: '100%', height: '400px' }}
+      />
     </Trap>
+    <hr />
+    <Trap {...props} />
+    <hr />
     <div style={bg}>
       {' '}
       Inaccessible