Editor: PostTitle: Decode entities for display

docs/manifest.json

@@ -695,6 +695,12 @@
 		"markdown_source": "../packages/components/src/date-time/README.md",
 		"parent": "components"
 	},
+	{
+		"title": "DetectFocusOutside",
+		"slug": "detect-focus-outside",
+		"markdown_source": "../packages/components/src/detect-focus-outside/README.md",
+		"parent": "components"
+	},
 	{
 		"title": "DimensionControl",
 		"slug": "dimension-control",

packages/components/src/detect-focus-outside/README.md

@@ -0,0 +1,36 @@
+# DetectFocusOutside
+
+`DetectFocusOutside` is a component used to help detect when focus leaves an element.
+
+This can be useful to disambiguate focus transitions within the same element. A React `blur` event will fire even when focus transitions to another element in the same context. `DetectFocusOutside` will only invoke its callback prop when focus has truly left the element.
+
+## Usage
+
+Wrap your rendered children with `DetectFocusOutside`, defining an `onFocusOutside` callback prop.
+
+```jsx
+import { DetectFocusOutside, TextControl } from '@wordpress/components';
+
+function MyComponent() {
+	function onFocusOutside() {
+		console.log( 'Focus has left the rendered element.' );
+	}
+
+	return (
+		<DetectFocusOutside onFocusOutside={ onFocusOutside }>
+			<TextControl />
+			<TextControl />
+		</DetectFocusOutside>
+	);
+);
+```
+
+In the above example, the `onFocusOutside` function is only called if focus leaves the element, and not if transitioning focus between the two inputs.
+
+## Props
+
+### `onFocusOutside`
+* **Type:** `Function`
+* **Required:** Yes
+
+A callback function to invoke when focus has left the rendered element. The callback will receive the original blur event.

packages/components/src/detect-focus-outside/index.js

@@ -0,0 +1,161 @@
+/**
+ * WordPress dependencies
+ */
+import { useRef, useEffect } from '@wordpress/element';
+
+/** @typedef {import('react').MouseEvent} ReactMouseEvent */
+/** @typedef {import('react').TouchEvent} ReactTouchEvent */
+/** @typedef {import('react').SyntheticEvent} ReactSyntheticEvent */
+/** @typedef {import('react').ReactNode} ReactNode */
+
+/**
+ * @typedef {(event:ReactSyntheticEvent)=>void} OnFocusOutsideProp
+ */
+
+/**
+ * Input types which are classified as button types, for use in considering
+ * whether element is a (focus-normalized) button.
+ *
+ * @type {Set<string>}
+ */
+const INPUT_BUTTON_TYPES = new Set( [ 'button', 'submit' ] );
+
+/**
+ * Event types which are classified as ends of interaction considered for focus
+ * event normalization.
+ *
+ * @type {Set<string>}
+ */
+const INTERACTION_END_TYPES = new Set( [ 'mouseup', 'touchend' ] );
+
+/**
+ * Returns true if the given element is a button element subject to focus
+ * normalization, or false otherwise.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#Clicking_and_focus
+ *
+ * @param {Element} element Element to test.
+ *
+ * @return {boolean} Whether element is a button.
+ */
+function isFocusNormalizedButton( element ) {
+	switch ( element.nodeName ) {
+		case 'A':
+		case 'BUTTON':
+			return true;
+
+		case 'INPUT':
+			const { type } = /** @type {HTMLInputElement} */ ( element );
+			return INPUT_BUTTON_TYPES.has( type );
+	}
+
+	return false;
+}
+
+/**
+ * Component used to help detect when focus leaves an element.
+ *
+ * This can be useful to disambiguate focus transitions within the same element.
+ * A React `blur` event will fire even when focus transitions to another element
+ * in the same context. `DetectFocusOutside` will only invoke its callback prop
+ * when focus has truly left the element
+ *
+ * @type {import('react').FC}
+ *
+ * @param {Object}             props                Component props.
+ * @param {OnFocusOutsideProp} props.onFocusOutside Callback function to invoke
+ *                                                  when focus has left the
+ *                                                  rendered element. The
+ *                                                  callback will receive the
+ *                                                  original blur event.
+ * @param {ReactNode}          props.children       Element children.
+ */
+function DetectFocusOutside( { children, onFocusOutside } ) {
+	const blurCheckTimeout = /** @type {import('react').MutableRefObject<number>} */ ( useRef() );
+	const preventBlurCheck = useRef( false );
+	useEffect( () => cancelBlurCheck );
+
+	/**
+	 * Cancels the scheduled blur check, if one is scheduled.
+	 */
+	function cancelBlurCheck() {
+		clearTimeout( blurCheckTimeout.current );
+	}
+
+	/**
+	 * Schedules a blur check to occur after the current call stack ends, during
+	 * which time it may be expected that the check is nullified based on other
+	 * interactions.
+	 *
+	 * @see normalizeButtonFocus
+	 *
+	 * @param {ReactSyntheticEvent} event Focus event.
+	 */
+	function queueBlurCheck( event ) {
+		// Skip blur check if clicking button. See `normalizeButtonFocus`.
+		if ( preventBlurCheck.current ) {
+			return;
+		}
+
+		// React does not allow using an event reference asynchronously due to
+		// recycling behavior, except when explicitly persisted.
+		event.persist();
+
+		blurCheckTimeout.current = setTimeout( () => {
+			// If document is not focused then focus should remain inside the
+			// wrapped component and therefore we cancel this blur event thereby
+			// leaving focus in place.
+			//
+			// See: https://developer.mozilla.org/en-US/docs/Web/API/Document/hasFocus
+			if ( document.hasFocus() ) {
+				onFocusOutside( event );
+			}
+		}, 0 );
+	}
+
+	/**
+	 * Handles a mousedown or mouseup event to respectively assign and unassign
+	 * a flag for preventing blur check on button elements. Some browsers,
+	 * namely Firefox and Safari, do not emit a focus event on button elements
+	 * when clicked, while others do. The logic here intends to normalize this
+	 * as treating click on buttons as focus.
+	 *
+	 * @see https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#Clicking_and_focus
+	 *
+	 * @param {ReactMouseEvent|ReactTouchEvent} event Event on which to base
+	 *                                                normalize.
+	 */
+	function normalizeButtonFocus( event ) {
+		const { type, target } = event;
+		if ( ! ( target instanceof window.Element ) ) {
+			return;
+		}
+
+		const isInteractionEnd = INTERACTION_END_TYPES.has( type );
+		if ( isInteractionEnd ) {
+			preventBlurCheck.current = false;
+		} else if ( isFocusNormalizedButton( target ) ) {
+			preventBlurCheck.current = true;
+		}
+	}
+
+	// Disable reason: See `normalizeButtonFocus` for browser-specific focus
+	// event normalization.
+
+	/* eslint-disable jsx-a11y/no-static-element-interactions */
+	return (
+		<div
+			onFocus={ cancelBlurCheck }
+			onMouseDown={ normalizeButtonFocus }
+			onMouseUp={ normalizeButtonFocus }
+			onTouchStart={ normalizeButtonFocus }
+			onTouchEnd={ normalizeButtonFocus }
+			onBlur={ queueBlurCheck }
+		>
+			{ children }
+		</div>
+	);
+	/* eslint-enable jsx-a11y/no-static-element-interactions */
+}
+
+export default DetectFocusOutside;

packages/components/src/detect-focus-outside/test/index.js

@@ -0,0 +1,119 @@
+/**
+ * External dependencies
+ */
+import TestUtils from 'react-dom/test-utils';
+
+/**
+ * WordPress dependencies
+ */
+import { Component } from '@wordpress/element';
+
+/**
+ * Internal dependencies
+ */
+import ReactDOM from 'react-dom';
+import DetectFocusOutside from '../';
+
+let wrapper, onFocusOutside;
+
+describe( 'DetectFocusOutside', () => {
+	let origHasFocus;
+
+	class TestComponent extends Component {
+		render() {
+			return (
+				<DetectFocusOutside
+					onFocusOutside={ this.props.onFocusOutside }
+				>
+					<input />
+					<input type="button" />
+				</DetectFocusOutside>
+			);
+		}
+	}
+
+	const simulateEvent = ( event, index = 0 ) => {
+		const element = TestUtils.scryRenderedDOMComponentsWithTag(
+			wrapper,
+			'input'
+		);
+		TestUtils.Simulate[ event ]( element[ index ] );
+	};
+
+	beforeEach( () => {
+		// Mock document.hasFocus() to always be true for testing
+		// note: we overide this for some tests.
+		origHasFocus = document.hasFocus;
+		document.hasFocus = () => true;
+
+		onFocusOutside = jest.fn();
+		wrapper = TestUtils.renderIntoDocument(
+			<TestComponent onFocusOutside={ onFocusOutside } />
+		);
+	} );
+
+	afterEach( () => {
+		document.hasFocus = origHasFocus;
+	} );
+
+	it( 'should not call handler if focus shifts to element within component', () => {
+		simulateEvent( 'focus' );
+		simulateEvent( 'blur' );
+		simulateEvent( 'focus', 1 );
+
+		jest.runAllTimers();
+
+		expect( onFocusOutside ).not.toHaveBeenCalled();
+	} );
+
+	it( 'should not call handler if focus transitions via click to button', () => {
+		simulateEvent( 'focus' );
+		simulateEvent( 'mouseDown', 1 );
+		simulateEvent( 'blur' );
+
+		// In most browsers, the input at index 1 would receive a focus event
+		// at this point, but this is not guaranteed, which is the intention of
+		// the normalization behavior tested here.
+		simulateEvent( 'mouseUp', 1 );
+
+		jest.runAllTimers();
+
+		expect( onFocusOutside ).not.toHaveBeenCalled();
+	} );
+
+	it( 'should call handler if focus doesn’t shift to element within component', () => {
+		simulateEvent( 'focus' );
+		simulateEvent( 'blur' );
+
+		jest.runAllTimers();
+
+		expect( onFocusOutside ).toHaveBeenCalled();
+	} );
+
+	it( 'should not call handler if focus shifts outside the component when the document does not have focus', () => {
+		// Force document.hasFocus() to return false to simulate the window/document losing focus
+		// See https://developer.mozilla.org/en-US/docs/Web/API/Document/hasFocus.
+		document.hasFocus = () => false;
+
+		simulateEvent( 'focus' );
+		simulateEvent( 'blur' );
+
+		jest.runAllTimers();
+
+		expect( onFocusOutside ).not.toHaveBeenCalled();
+	} );
+
+	it( 'should cancel check when unmounting while queued', () => {
+		simulateEvent( 'focus' );
+		simulateEvent( 'input' );
+
+		ReactDOM.unmountComponentAtNode(
+			// eslint-disable-next-line react/no-find-dom-node
+			ReactDOM.findDOMNode( wrapper ).parentNode
+		);
+
+		jest.runAllTimers();
+
+		expect( onFocusOutside ).not.toHaveBeenCalled();
+	} );
+} );

packages/components/src/higher-order/with-focus-outside/README.md

@@ -1,3 +1,5 @@
+>⚠️ **Note:** While this higher-order component is not officially deprecated, you should consider using the [`DetectFocusOutside` component](../../detect-focus-outside) instead. This higher-order component _does not_ and will never support being used by function components.
+
 # withFocusOutside
 
 `withFocusOutside` is a React [higher-order component](https://facebook.github.io/react/docs/higher-order-components.html) to enable behavior to occur when focus leaves an element. Since a `blur` event will fire in React even when focus transitions to another element in the same context, this higher-order component encapsulates the logic necessary to determine if focus has truly left the element.