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Refactor Hoverable component into functional #29052

325 changes: 172 additions & 153 deletions src/components/Hoverable/index.js
Original file line number Diff line number Diff line change
@@ -1,197 +1,216 @@
import _ from 'underscore';
import React, {Component} from 'react';
import React, {useEffect, useCallback, useState, useRef, useMemo, useImperativeHandle} from 'react';
import {DeviceEventEmitter} from 'react-native';
import {propTypes, defaultProps} from './hoverablePropTypes';
import * as DeviceCapabilities from '../../libs/DeviceCapabilities';
import CONST from '../../CONST';

/**
* Maps the children of a Hoverable component to
* - a function that is called with the parameter
* - the child itself if it is the only child
* @param {Array|Function|ReactNode} children - The children to map.
* @param {Object} callbackParam - The parameter to pass to the children function.
* @returns {ReactNode} The mapped children.
*/
function mapChildren(children, callbackParam) {
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I think about adding comments for mapChildren and assignRef to clarify why we have this logic.

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Thanks for the idea, done ✅

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Thank you, looks good!

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@kacper-mikolajczak, do we need to extract this logic outside of the component? Usually, if logic is extracted should be moved to utils or helpers dir

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@kacper-mikolajczak kacper-mikolajczak Oct 9, 2023

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@ArekChr Those helpers are not really that universal to move them into utils - I did not want to bloat the component body no more, thus extracted them away. This might help to reduce the cognitive load when studying the component, wdyt?

If not, is there a convention we use for such local helpers? Shall we create a separate file under component's directory called utils/helpers?

Thanks for pointing this out!

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I agree that local functions simplify readability. For me, it can stay as it is. But assignRef seems to be a universal function. It could be moved to, e.g. react utils or helpers. @Beamanator, any thoughts?

if (_.isArray(children) && children.length === 1) {
return children[0];
}

if (_.isFunction(children)) {
return children(callbackParam);
}

return children;
}

/**
* Assigns a ref to an element, either by setting the current property of the ref object or by calling the ref function
* @param {Object|Function} ref - The ref object or function.
* @param {HTMLElement} el - The element to assign the ref to.
*/
function assignRef(ref, el) {
if (!ref) {
return;
}

if (_.has(ref, 'current')) {
// eslint-disable-next-line no-param-reassign
ref.current = el;
}

if (_.isFunction(ref)) {
ref(el);
}
}

/**
* It is necessary to create a Hoverable component instead of relying solely on Pressable support for hover state,
* because nesting Pressables causes issues where the hovered state of the child cannot be easily propagated to the
* parent. https://github.com/necolas/react-native-web/issues/1875
*/
class Hoverable extends Component {
constructor(props) {
super(props);

this.handleVisibilityChange = this.handleVisibilityChange.bind(this);
this.checkHover = this.checkHover.bind(this);
const Hoverable = React.forwardRef(({disabled, onHoverIn, onHoverOut, onMouseEnter, onMouseLeave, children, shouldHandleScroll}, outerRef) => {
const [isHovered, setIsHovered] = useState(false);

this.state = {
isHovered: false,
};
const isScrolling = useRef(false);
const isHoveredRef = useRef(false);
const ref = useRef(null);

this.isHoveredRef = false;
this.isScrollingRef = false;
this.wrapperView = null;
}
const updateIsHoveredOnScrolling = useCallback(
(hovered) => {
if (disabled) {
return;
}

componentDidMount() {
document.addEventListener('visibilitychange', this.handleVisibilityChange);
document.addEventListener('mouseover', this.checkHover);
isHoveredRef.current = hovered;

/**
* Only add the scrolling listener if the shouldHandleScroll prop is true
* and the scrollingListener is not already set.
*/
if (!this.scrollingListener && this.props.shouldHandleScroll) {
this.scrollingListener = DeviceEventEmitter.addListener(CONST.EVENTS.SCROLLING, (scrolling) => {
/**
* If user has stopped scrolling and the isHoveredRef is true, then we should update the hover state.
*/
if (!scrolling && this.isHoveredRef) {
this.setState({isHovered: this.isHoveredRef}, this.props.onHoverIn);
} else if (scrolling && this.isHoveredRef) {
/**
* If the user has started scrolling and the isHoveredRef is true, then we should set the hover state to false.
* This is to hide the existing hover and reaction bar.
*/
this.setState({isHovered: false}, this.props.onHoverOut);
}
this.isScrollingRef = scrolling;
});
}
}
if (shouldHandleScroll && isScrolling.current) {
return;
}
setIsHovered(hovered);
},
[disabled, shouldHandleScroll],
);

useEffect(() => {
const unsetHoveredWhenDocumentIsHidden = () => document.visibilityState === 'hidden' && setIsHovered(false);

document.addEventListener('visibilitychange', unsetHoveredWhenDocumentIsHidden);

componentDidUpdate(prevProps) {
if (prevProps.disabled === this.props.disabled) {
return () => document.removeEventListener('visibilitychange', unsetHoveredWhenDocumentIsHidden);
}, []);

useEffect(() => {
if (!shouldHandleScroll) {
return;
}

if (this.props.disabled && this.state.isHovered) {
this.setState({isHovered: false});
}
}
const scrollingListener = DeviceEventEmitter.addListener(CONST.EVENTS.SCROLLING, (scrolling) => {
isScrolling.current = scrolling;
if (!scrolling) {
setIsHovered(isHoveredRef.current);
}
});

componentWillUnmount() {
document.removeEventListener('visibilitychange', this.handleVisibilityChange);
document.removeEventListener('mouseover', this.checkHover);
if (this.scrollingListener) {
this.scrollingListener.remove();
}
}
return () => scrollingListener.remove();
}, [shouldHandleScroll]);

/**
* Sets the hover state of this component to true and execute the onHoverIn callback.
*
* @param {Boolean} isHovered - Whether or not this component is hovered.
*/
setIsHovered(isHovered) {
if (this.props.disabled) {
useEffect(() => {
if (!DeviceCapabilities.hasHoverSupport()) {
return;
}

/**
* Capture whther or not the user is hovering over the component.
* We will use this to determine if we should update the hover state when the user has stopped scrolling.
* Checks the hover state of a component and updates it based on the event target.
* This is necessary to handle cases where the hover state might get stuck due to an unreliable mouseleave trigger,
* such as when an element is removed before the mouseleave event is triggered.
* @param {Event} e - The hover event object.
*/
this.isHoveredRef = isHovered;
const unsetHoveredIfOutside = (e) => {
if (!ref.current || !isHovered) {
return;
}

/**
* If the isScrollingRef is true, then the user is scrolling and we should not update the hover state.
*/
if (this.isScrollingRef && this.props.shouldHandleScroll && !this.state.isHovered) {
return;
}
if (ref.current.contains(e.target)) {
return;
}

if (isHovered !== this.state.isHovered) {
this.setState({isHovered}, isHovered ? this.props.onHoverIn : this.props.onHoverOut);
}
}
setIsHovered(false);
};

/**
* Checks the hover state of a component and updates it based on the event target.
* This is necessary to handle cases where the hover state might get stuck due to an unreliable mouseleave trigger,
* such as when an element is removed before the mouseleave event is triggered.
* @param {Event} e - The hover event object.
*/
checkHover(e) {
if (!this.wrapperView || !this.state.isHovered) {
return;
}
document.addEventListener('mouseover', unsetHoveredIfOutside);

if (this.wrapperView.contains(e.target)) {
return;
}

this.setIsHovered(false);
}
return () => document.removeEventListener('mouseover', unsetHoveredIfOutside);
}, [isHovered]);

handleVisibilityChange() {
if (document.visibilityState !== 'hidden') {
useEffect(() => {
if (!disabled || !isHovered) {
return;
}
setIsHovered(false);
}, [disabled, isHovered]);

this.setIsHovered(false);
}

render() {
let child = this.props.children;
if (_.isArray(this.props.children) && this.props.children.length === 1) {
child = this.props.children[0];
useEffect(() => {
if (disabled) {
return;
}

if (_.isFunction(child)) {
child = child(this.state.isHovered);
if (onHoverIn && isHovered) {
return onHoverIn();
}

if (!DeviceCapabilities.hasHoverSupport()) {
return child;
if (onHoverOut && !isHovered) {
return onHoverOut();
}

return React.cloneElement(React.Children.only(child), {
ref: (el) => {
this.wrapperView = el;

// Call the original ref, if any
const {ref} = child;
if (_.isFunction(ref)) {
ref(el);
return;
}

if (_.isObject(ref)) {
ref.current = el;
}
},
onMouseEnter: (el) => {
if (_.isFunction(this.props.onMouseEnter)) {
this.props.onMouseEnter(el);
}

this.setIsHovered(true);

if (_.isFunction(child.props.onMouseEnter)) {
child.props.onMouseEnter(el);
}
},
onMouseLeave: (el) => {
if (_.isFunction(this.props.onMouseLeave)) {
this.props.onMouseLeave(el);
}

this.setIsHovered(false);

if (_.isFunction(child.props.onMouseLeave)) {
child.props.onMouseLeave(el);
}
},
onBlur: (el) => {
// Check if the blur event occurred due to clicking outside the element
// and the wrapperView contains the element that caused the blur and reset isHovered
if (!this.wrapperView.contains(el.target) && !this.wrapperView.contains(el.relatedTarget)) {
this.setIsHovered(false);
}

if (_.isFunction(child.props.onBlur)) {
child.props.onBlur(el);
}
},
});
}, [disabled, isHovered, onHoverIn, onHoverOut]);

// Expose inner ref to parent through outerRef. This enable us to use ref both in parent and child.
useImperativeHandle(outerRef, () => ref.current, []);

const child = useMemo(() => React.Children.only(mapChildren(children, isHovered)), [children, isHovered]);

const enableHoveredOnMouseEnter = useCallback(
(el) => {
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updateIsHoveredOnScrolling(true);

if (_.isFunction(onMouseEnter)) {
onMouseEnter(el);
}

if (_.isFunction(child.props.onMouseEnter)) {
child.props.onMouseEnter(el);
}
},
[child.props, onMouseEnter, updateIsHoveredOnScrolling],
);

const disableHoveredOnMouseLeave = useCallback(
(el) => {
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updateIsHoveredOnScrolling(false);

if (_.isFunction(onMouseLeave)) {
onMouseLeave(el);
}

if (_.isFunction(child.props.onMouseLeave)) {
child.props.onMouseLeave(el);
}
},
[child.props, onMouseLeave, updateIsHoveredOnScrolling],
);

const disableHoveredOnBlur = useCallback(
(el) => {
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// Check if the blur event occurred due to clicking outside the element
// and the wrapperView contains the element that caused the blur and reset isHovered
if (!ref.current.contains(el.target) && !ref.current.contains(el.relatedTarget)) {
setIsHovered(false);
}

if (_.isFunction(child.props.onBlur)) {
child.props.onBlur(el);
}
},
[child.props],
);

if (!DeviceCapabilities.hasHoverSupport()) {
return child;
}
}

return React.cloneElement(child, {
ref: (el) => {
ref.current = el;
assignRef(child.ref, el);
},
onMouseEnter: enableHoveredOnMouseEnter,
onMouseLeave: disableHoveredOnMouseLeave,
onBlur: disableHoveredOnBlur,
});
});

Hoverable.propTypes = propTypes;
Hoverable.defaultProps = defaultProps;
Hoverable.displayName = 'Hoverable';

export default Hoverable;
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