compat/src/render.js - main - githubmirror/preact

compat/src/render.js
412 строк12 KB
Jovi De Croock
Golf: loose equality where the operands make it identical
06 авг 2026, 18:59
06 авг 2026, 18:595e96b7a
import {
	render as preactRender,
	hydrate as preactHydrate,
	options,
	toChildArray,
	Component
} from 'preact';
import {
	useCallback,
	useContext,
	useDebugValue,
	useEffect,
	useId,
	useImperativeHandle,
	useLayoutEffect,
	useMemo,
	useReducer,
	useRef,
	useState
} from 'preact/hooks';
import { useDeferredValue, useInsertionEffect, useTransition } from './index';
import { assign, IS_NON_DIMENSIONAL } from './util';

export const REACT_ELEMENT_TYPE = Symbol.for('react.element');

const MODE_HYDRATE = 1 << 5;

const CAMEL_PROPS =
	/^(?:accent|alignment|arabic|baseline|cap|clip(?!PathU)|color|dominant|fill|flood|font|glyph(?!R)|horiz|image(!S)|letter|lighting|marker(?!H|W|U)|overline|paint|pointer|shape|stop|strikethrough|stroke|text(?!L)|transform|underline|unicode|units|v|vector|vert|word|writing|x(?!C))[A-Z]/;
const CAMEL_REPLACE = /[A-Z0-9]/g;
const IS_DOM = typeof document != 'undefined';

/**
 * This is taken from https://github.com/facebook/react/blob/main/packages/use-sync-external-store/src/useSyncExternalStoreShimClient.js#L84
 * on a high level this cuts out the warnings, ... and attempts a smaller implementation
 * @typedef {{ _value: any; _getSnapshot: () => any }} Store
 */
export function useSyncExternalStore(
	subscribe,
	getSnapshot,
	getServerSnapshot
) {
	const serverRendering = options._skipEffects || hydrationRoot;
	const value = serverRendering
		? (getServerSnapshot || getSnapshot)()
		: getSnapshot();

	/**
	 * @typedef {{ _instance: Store }} StoreRef
	 * @type {[StoreRef, (store: StoreRef) => void]}
	 */
	const [{ _instance }, forceUpdate] = useState({
		_instance: { _value: value, _getSnapshot: getSnapshot }
	});

	useLayoutEffect(() => {
		_instance._value = value;
		_instance._getSnapshot = getSnapshot;

		if (didSnapshotChange(_instance)) {
			forceUpdate({ _instance });
		}
	}, [subscribe, value, getSnapshot]);

	useEffect(() => {
		if (didSnapshotChange(_instance)) {
			forceUpdate({ _instance });
		}

		return subscribe(() => {
			if (didSnapshotChange(_instance)) {
				forceUpdate({ _instance });
			}
		});
	}, [subscribe]);

	return value;
}

/** @type {(inst: Store) => boolean} */
function didSnapshotChange(inst) {
	try {
		return !Object.is(inst._value, inst._getSnapshot());
	} catch (error) {
		return true;
	}
}

// Input types for which onchange should not be converted to oninput.
const onChangeInputType = type => /fil|che|rad/.test(type);

// Some libraries like `react-virtualized` explicitly check for this.
Component.prototype.isReactComponent = true;

// `UNSAFE_*` lifecycle hooks
// Preact only ever invokes the unprefixed methods.
// Here we provide a base "fallback" implementation that calls any defined UNSAFE_ prefixed method.
// - If a component defines its own `componentDidMount()` (including via defineProperty), use that.
// - If a component defines `UNSAFE_componentDidMount()`, `componentDidMount` is the alias getter/setter.
// - If anything assigns to an `UNSAFE_*` property, the assignment is forwarded to the unprefixed property.
// See https://github.com/preactjs/preact/issues/1941
[
	'componentWillMount',
	'componentWillReceiveProps',
	'componentWillUpdate'
].forEach(key => {
	Object.defineProperty(Component.prototype, key, {
		configurable: true,
		get() {
			return this['UNSAFE_' + key];
		},
		set(v) {
			Object.defineProperty(this, key, {
				configurable: true,
				writable: true,
				value: v
			});
		}
	});
});

/**
 * Proxy render() since React returns a Component reference.
 * @param {import('./internal').VNode} vnode VNode tree to render
 * @param {import('./internal').PreactElement} parent DOM node to render vnode tree into
 * @param {() => void} [callback] Optional callback that will be called after rendering
 * @returns {import('./internal').Component | null} The root component reference or null
 */
export function render(vnode, parent, callback) {
	// React destroys any existing DOM nodes, see #1727
	// ...but only on the first render, see #1828
	if (parent._children == null) {
		parent.textContent = '';
	}

	preactRender(vnode, parent);
	if (typeof callback == 'function') callback();

	return vnode ? vnode._component : null;
}

export function hydrate(vnode, parent, callback) {
	preactHydrate(vnode, parent);
	if (typeof callback == 'function') callback();

	return vnode ? vnode._component : null;
}

let oldEventHook = options.event;
options.event = e => {
	if (oldEventHook) e = oldEventHook(e);

	e.persist = () => {};
	e.isPropagationStopped = function isPropagationStopped() {
		return this.cancelBubble;
	};
	e.isDefaultPrevented = function isDefaultPrevented() {
		return this.defaultPrevented;
	};
	return (e.nativeEvent = e);
};

const classNameDescriptorNonEnumberable = {
	configurable: true,
	get() {
		return this.class;
	}
};

function handleDomVNode(vnode) {
	let props = vnode.props,
		type = vnode.type,
		normalizedProps = {},
		isNonDashedType = type.indexOf('-') == -1;

	for (let i in props) {
		let value = props[i];

		if (
			(i == 'value' && 'defaultValue' in props && value == null) ||
			// Emulate React's behavior of not rendering the contents of noscript tags on the client.
			(IS_DOM && i == 'children' && type == 'noscript') ||
			i == 'class' ||
			i == 'className'
		) {
			// Skip applying value if it is null/undefined and we already set
			// a default value
			continue;
		}

		if (i == 'style' && typeof value == 'object') {
			let cloned;
			for (let key in value) {
				if (typeof value[key] == 'number' && !IS_NON_DIMENSIONAL.test(key)) {
					if (!cloned) {
						cloned = value = assign({}, value);
					}
					value[key] += 'px';
				}
			}
		} else if (i == 'defaultValue' && 'value' in props && props.value == null) {
			// `defaultValue` is treated as a fallback `value` when a value prop is present but null/undefined.
			// `defaultValue` for Elements with no value prop is the same as the DOM defaultValue property.
			i = 'value';
		} else if (i == 'download' && value === true) {
			// Calling `setAttribute` with a truthy value will lead to it being
			// passed as a stringified value, e.g. `download="true"`. React
			// converts it to an empty string instead, otherwise the attribute
			// value will be used as the file name and the file will be called
			// "true" upon downloading it.
			value = '';
		} else if (i == 'translate' && value === 'no') {
			value = false;
		} else if (i[0] == 'o' && i[1] == 'n') {
			let lowerCased = i.toLowerCase();
			if (lowerCased == 'ondoubleclick') {
				i = 'ondblclick';
			} else if (
				lowerCased == 'onchange' &&
				(type == 'input' || type == 'textarea') &&
				!onChangeInputType(props.type)
			) {
				lowerCased = i = 'oninput';
			} else if (lowerCased == 'onfocus') {
				i = 'onfocusin';
			} else if (lowerCased == 'onblur') {
				i = 'onfocusout';
			}

			// Add support for onInput and onChange, see #3561
			// if we have an oninput prop already change it to oninputCapture
			if (lowerCased == 'oninput') {
				i = lowerCased;
				if (normalizedProps[i]) {
					i = 'oninputCapture';
				}
			}
		} else if (isNonDashedType && CAMEL_PROPS.test(i)) {
			i = i.replace(CAMEL_REPLACE, '-$&').toLowerCase();
		} else if (value === null) {
			value = undefined;
		}

		normalizedProps[i] = value;
	}

	if (type == 'select') {
		// Add support for array select values: <select multiple value={[]} />
		if (normalizedProps.multiple && Array.isArray(normalizedProps.value)) {
			// forEach() always returns undefined, which we abuse here to unset the value prop.
			normalizedProps.value = toChildArray(props.children).forEach(child => {
				child.props.selected =
					normalizedProps.value.indexOf(child.props.value) != -1;
			});
		}

		// Adding support for defaultValue in select tag
		if (normalizedProps.defaultValue != null) {
			normalizedProps.value = toChildArray(props.children).forEach(child => {
				if (normalizedProps.multiple) {
					child.props.selected =
						normalizedProps.defaultValue.indexOf(child.props.value) != -1;
				} else {
					child.props.selected =
						normalizedProps.defaultValue == child.props.value;
				}
			});
		}
	}

	if (props.class && !props.className) {
		normalizedProps.class = props.class;
		Object.defineProperty(
			normalizedProps,
			'className',
			classNameDescriptorNonEnumberable
		);
	} else if (props.className) {
		normalizedProps.class = normalizedProps.className = props.className;
	}

	vnode.props = normalizedProps;
}

let oldVNodeHook = options.vnode;
options.vnode = vnode => {
	// only normalize props on Element nodes
	if (typeof vnode.type == 'string') {
		handleDomVNode(vnode);
	} else if (typeof vnode.type == 'function') {
		const shouldApplyRef =
			'prototype' in vnode.type && vnode.type.prototype.render;
		if ('ref' in vnode.props && shouldApplyRef) {
			vnode.ref = vnode.props.ref;
			delete vnode.props.ref;
		}

		if (vnode.type.defaultProps) {
			let normalizedProps = assign({}, vnode.props);
			for (let i in vnode.type.defaultProps) {
				if (normalizedProps[i] === undefined) {
					normalizedProps[i] = vnode.type.defaultProps[i];
				}
			}
			vnode.props = normalizedProps;
		}
	}
	vnode.$$typeof = REACT_ELEMENT_TYPE;

	if (oldVNodeHook) oldVNodeHook(vnode);
};

// Only needed for react-relay
let currentComponent, hydrationRoot;
const oldBeforeRender = options._render;
options._render = function (vnode) {
	if (oldBeforeRender) {
		oldBeforeRender(vnode);
	}
	if (vnode._flags & MODE_HYDRATE) hydrationRoot = vnode;
	currentComponent = vnode._component;
};

const oldDiffed = options.diffed;
/** @type {(vnode: import('./internal').VNode) => void} */
options.diffed = function (vnode) {
	if (oldDiffed) {
		oldDiffed(vnode);
	}

	const props = vnode.props;
	const dom = vnode._dom;

	if (
		dom != null &&
		vnode.type == 'textarea' &&
		'value' in props &&
		props.value !== dom.value
	) {
		dom.value = props.value == null ? '' : props.value;
	}

	currentComponent = null;
	if (hydrationRoot == vnode) hydrationRoot = null;
};

/**
 * Read the value of a Promise (suspending while pending) or a Context.
 * Unlike other hooks, `use` may be called conditionally.
 * @template T
 * @param {(Promise<T> & { status?: string, value?: T, reason?: any }) | import('../../src/internal').PreactContext} resource
 * @returns {T}
 */
export const use = resource => {
	// A Context is a function without a `then`, a thenable has one.
	if (resource.then) {
		if (resource.status == 'fulfilled') return resource.value;
		if (resource.status == 'rejected') throw resource.reason;
		if (!resource.status) {
			resource.status = 'pending';
			resource.then(
				value => {
					resource.status = 'fulfilled';
					resource.value = value;
				},
				reason => {
					resource.status = 'rejected';
					resource.reason = reason;
				}
			);
		}
		throw resource;
	}

	const id = resource._id;
	const provider = currentComponent._globalContext[id];
	if (!provider) return resource._defaultValue;
	// `use` runs on every render without hook state, while `provider.sub`
	// wraps `componentWillUnmount` on each call — mark the component so we
	// only subscribe it once.
	if (!currentComponent[id]) {
		currentComponent[id] = true;
		provider.sub(currentComponent);
	}
	return provider.props.value;
};

// This is a very very private internal function for React it
// is used to sort-of do runtime dependency injection.
export const __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED = {
	ReactCurrentDispatcher: {
		current: {
			readContext: use,
			useCallback,
			useContext,
			useDebugValue,
			useDeferredValue,
			useEffect,
			useId,
			useImperativeHandle,
			useInsertionEffect,
			useLayoutEffect,
			useMemo,
			// useMutableSource, // experimental-only and replaced by uSES, likely not worth supporting
			useReducer,
			useRef,
			useState,
			useSyncExternalStore,
			useTransition
		}
	}
};