Components: Shift focus into popover when opened

components/popover/index.js

@@ -8,6 +8,7 @@ import { isEqual, noop } from 'lodash';
  * WordPress dependencies
  */
 import { createPortal, Component } from '@wordpress/element';
+import { focus } from '@wordpress/utils';
 
 /**
  * Internal dependencies
@@ -24,6 +25,7 @@ export class Popover extends Component {
 	constructor() {
 		super( ...arguments );
 
+		this.focus = this.focus.bind( this );
 		this.bindNode = this.bindNode.bind( this );
 		this.setOffset = this.setOffset.bind( this );
 		this.throttledSetOffset = this.throttledSetOffset.bind( this );
@@ -58,6 +60,10 @@ export class Popover extends Component {
 		const { isOpen: prevIsOpen, position: prevPosition } = prevProps;
 		if ( isOpen !== prevIsOpen ) {
 			this.toggleWindowEvents( isOpen );
+
+			if ( isOpen ) {
+				this.focus();
+			}
 		}
 
 		if ( ! isOpen ) {
@@ -85,6 +91,22 @@ export class Popover extends Component {
 		window[ handler ]( 'scroll', this.throttledSetOffset );
 	}
 
+	focus() {
+		const { content, popover } = this.nodes;
+		if ( ! content ) {
+			return;
+		}
+
+		// Find first tabbable node within content and shift focus, falling
+		// back to the popover panel itself.
+		const firstTabbable = focus.tabbable.find( content )[ 0 ];
+		if ( firstTabbable ) {
+			firstTabbable.focus();
+		} else if ( popover ) {
+			popover.focus();
+		}
+	}
+
 	throttledSetOffset() {
 		this.rafHandle = window.requestAnimationFrame( this.setOffset );
 	}

editor/inserter/menu.js

@@ -356,15 +356,13 @@ export class InserterMenu extends Component {
 					{ __( 'Search blocks' ) }
 				</label>
 				<input
-					autoFocus
 					id={ `editor-inserter__search-${ instanceId }` }
 					type="search"
 					placeholder={ __( 'Search…' ) }
 					className="editor-inserter__search"
 					onChange={ this.filter }
 					onClick={ this.setSearchFocus }
 					ref={ this.bindReferenceNode( 'search' ) }
-					tabIndex="-1"
 				/>
 				<div role="menu" className="editor-inserter__content"
 					ref={ ( ref ) => this.tabContainer = ref }>

utils/focus/focusable.js

@@ -0,0 +1,93 @@
+/**
+ * External dependencies
+ */
+import 'element-closest';
+
+/**
+ * References:
+ *
+ * Focusable:
+ *  - https://www.w3.org/TR/html5/editing.html#focus-management
+ *
+ * Sequential focus navigation:
+ *  - https://www.w3.org/TR/html5/editing.html#sequential-focus-navigation-and-the-tabindex-attribute
+ *
+ * Disabled elements:
+ *  - https://www.w3.org/TR/html5/disabled-elements.html#disabled-elements
+ *
+ * getClientRects algorithm (requiring layout box):
+ *  - https://www.w3.org/TR/cssom-view-1/#extension-to-the-element-interface
+ *
+ * AREA elements associated with an IMG:
+ *  - https://w3c.github.io/html/editing.html#data-model
+ */
+
+const SELECTOR = [
+	'[tabindex]',
+	'a[href]',
+	'button:not([disabled])',
+	'input:not([type="hidden"]):not([disabled])',
+	'select:not([disabled])',
+	'textarea:not([disabled])',
+	'iframe',
+	'object',
+	'embed',
+	'area[href]',
+	'[contenteditable]',
+].join( ',' );
+
+/**
+ * Returns true if the specified element is visible (i.e. neither display: none
+ * nor visibility: hidden).
+ *
+ * @param  {Element} element DOM element to test
+ * @return {Boolean}         Whether element is visible
+ */
+function isVisible( element ) {
+	return (
+		element.offsetWidth > 0 ||
+		element.offsetHeight > 0 ||
+		element.getClientRects().length > 0
+	);
+}
+
+/**
+ * Returns true if the specified area element is a valid focusable element, or
+ * false otherwise. Area is only focusable if within a map where a named map
+ * referenced by an image somewhere in the document.
+ *
+ * @param  {Element} element DOM area element to test
+ * @return {Boolean}         Whether area element is valid for focus
+ */
+function isValidFocusableArea( element ) {
+	const map = element.closest( 'map[name]' );
+	if ( ! map ) {
+		return false;
+	}
+
+	const img = document.querySelector( 'img[usemap="#' + map.name + '"]' );
+	return !! img && isVisible( img );
+}
+
+/**
+ * Returns all focusable elements within a given context.
+ *
+ * @param  {Element}   context Element in which to search
+ * @return {Element[]}         Focusable elements
+ */
+export function find( context ) {
+	const elements = context.querySelectorAll( SELECTOR );
+
+	return [ ...elements ].filter( ( element ) => {
+		if ( ! isVisible( element ) ) {
+			return false;
+		}
+
+		const { nodeName } = element;
+		if ( 'AREA' === nodeName ) {
+			return isValidFocusableArea( element );
+		}
+
+		return true;
+	} );
+}

utils/focus/index.js

@@ -0,0 +1,4 @@
+import * as focusable from './focusable';
+import * as tabbable from './tabbable';
+
+export { focusable, tabbable };

utils/focus/tabbable.js

@@ -0,0 +1,64 @@
+/**
+ * Internal dependencies
+ */
+import { find as findFocusable } from './focusable';
+
+/**
+ * Returns true if the specified element is tabbable, or false otherwise.
+ *
+ * @param  {Element} element Element to test
+ * @return {Boolean}         Whether element is tabbable
+ */
+function isTabbableIndex( element ) {
+	return element.tabIndex !== -1;
+}
+
+/**
+ * An array map callback, returning an object with the element value and its
+ * array index location as properties. This is used to emulate a proper stable
+ * sort where equal tabIndex should be left in order of their occurrence in the
+ * document.
+ *
+ * @param  {Element} element Element
+ * @param  {Number}  index   Array index of element
+ * @return {Object}          Mapped object with element, index
+ */
+function mapElementToObjectTabbable( element, index ) {
+	return { element, index };
+}
+
+/**
+ * An array map callback, returning an element of the given mapped object's
+ * element value.
+ *
+ * @param  {Object}  object Mapped object with index
+ * @return {Element}        Mapped object element
+ */
+function mapObjectTabbableToElement( object ) {
+	return object.element;
+}
+
+/**
+ * A sort comparator function used in comparing two objects of mapped elements.
+ *
+ * @see mapElementToObjectTabbable
+ *
+ * @param  {Object} a First object to compare
+ * @param  {Object} b Second object to compare
+ * @return {Number}   Comparator result
+ */
+function compareObjectTabbables( a, b ) {
+	if ( a.element.tabIndex === b.element.tabIndex ) {
+		return a.index - b.index;
+	}
+
+	return a.element.tabIndex - b.element.tabIndex;
+}
+
+export function find( context ) {
+	return findFocusable( context )
+		.filter( isTabbableIndex )
+		.map( mapElementToObjectTabbable )
+		.sort( compareObjectTabbables )
+		.map( mapObjectTabbableToElement );
+}

utils/focus/test/focusable.js

@@ -0,0 +1,140 @@
+/**
+ * Internal dependencies
+ */
+import createElement from './utils/create-element';
+import { find } from '../focusable';
+
+describe( 'focusable', () => {
+	beforeEach( () => {
+		document.body.innerHTML = '';
+	} );
+
+	describe( 'find()', () => {
+		it( 'returns empty array if no children', () => {
+			const node = createElement( 'div' );
+
+			expect( find( node ) ).toEqual( [] );
+		} );
+
+		it( 'returns empty array if no focusable children', () => {
+			const node = createElement( 'div' );
+			node.appendChild( createElement( 'div' ) );
+
+			expect( find( node ) ).toEqual( [] );
+		} );
+
+		it( 'returns array of focusable children', () => {
+			const node = createElement( 'div' );
+			node.appendChild( createElement( 'input' ) );
+
+			const focusable = find( node );
+
+			expect( focusable ).toHaveLength( 1 );
+			expect( focusable[ 0 ].nodeName ).toBe( 'INPUT' );
+		} );
+
+		it( 'finds nested focusable child', () => {
+			const node = createElement( 'div' );
+			node.appendChild( createElement( 'div' ) );
+			node.firstChild.appendChild( createElement( 'input' ) );
+
+			const focusable = find( node );
+
+			expect( focusable ).toHaveLength( 1 );
+			expect( focusable[ 0 ].nodeName ).toBe( 'INPUT' );
+		} );
+
+		it( 'finds link with no href but tabindex', () => {
+			const node = createElement( 'div' );
+			const link = createElement( 'a' );
+			link.tabIndex = 0;
+			node.appendChild( link );
+
+			expect( find( node ) ).toEqual( [ link ] );
+		} );
+
+		it( 'finds valid area focusable', () => {
+			const map = createElement( 'map' );
+			map.name = 'testfocus';
+			const area = createElement( 'area' );
+			area.href = '';
+			map.appendChild( area );
+			const img = createElement( 'img' );
+			img.setAttribute( 'usemap', '#testfocus' );
+			document.body.appendChild( map );
+			document.body.appendChild( img );
+
+			const focusable = find( map );
+
+			expect( focusable ).toHaveLength( 1 );
+			expect( focusable[ 0 ].nodeName ).toBe( 'AREA' );
+		} );
+
+		it( 'ignores invalid area focusable', () => {
+			const map = createElement( 'map' );
+			map.name = 'testfocus';
+			const area = createElement( 'area' );
+			area.href = '';
+			map.appendChild( area );
+			const img = createElement( 'img' );
+			img.setAttribute( 'usemap', '#testfocus' );
+			img.style.display = 'none';
+			document.body.appendChild( map );
+			document.body.appendChild( img );
+
+			expect( find( map ) ).toEqual( [] );
+		} );
+
+		it( 'ignores invisible inputs', () => {
+			const node = createElement( 'div' );
+			const input = createElement( 'input' );
+			node.appendChild( input );
+
+			input.style.visibility = 'hidden';
+			expect( find( node ) ).toEqual( [] );
+
+			input.style.visibility = 'visible';
+			input.style.display = 'none';
+			expect( find( node ) ).toEqual( [] );
+
+			input.style.display = 'inline-block';
+			const focusable = find( node );
+			expect( focusable ).toHaveLength( 1 );
+			expect( focusable[ 0 ].nodeName ).toBe( 'INPUT' );
+		} );
+
+		it( 'ignores inputs in invisible ancestors', () => {
+			const node = createElement( 'div' );
+			const input = createElement( 'input' );
+			node.appendChild( input );
+
+			node.style.visibility = 'hidden';
+			expect( find( node ) ).toEqual( [] );
+
+			node.style.visibility = 'visible';
+			node.style.display = 'none';
+			expect( find( node ) ).toEqual( [] );
+
+			node.style.display = 'block';
+			const focusable = find( node );
+			expect( focusable ).toHaveLength( 1 );
+			expect( focusable[ 0 ].nodeName ).toBe( 'INPUT' );
+		} );
+
+		it( 'does not return context even if focusable', () => {
+			const node = createElement( 'div' );
+			node.tabIndex = 0;
+
+			expect( find( node ) ).toEqual( [] );
+		} );
+
+		it( 'limits found focusables to specific context', () => {
+			const node = createElement( 'div' );
+			node.appendChild( createElement( 'div' ) );
+			document.body.appendChild( node );
+			document.body.appendChild( createElement( 'input' ) );
+
+			expect( find( node ) ).toEqual( [] );
+		} );
+	} );
+} );