watchpack - npm Package Compare versions

Comparing version 2.4.4 to 2.5.0

lib/index.js

+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+"use strict";
+
+const { EventEmitter } = require("events");
+const globToRegExp = require("glob-to-regexp");
+const LinkResolver = require("./LinkResolver");
+const getWatcherManager = require("./getWatcherManager");
+const watchEventSource = require("./watchEventSource");
+
+/** @typedef {import("./getWatcherManager").WatcherManager} WatcherManager */
+/** @typedef {import("./DirectoryWatcher")} DirectoryWatcher */
+/** @typedef {import("./DirectoryWatcher").DirectoryWatcherEvents} DirectoryWatcherEvents */
+/** @typedef {import("./DirectoryWatcher").FileWatcherEvents} FileWatcherEvents */
+
+// eslint-disable-next-line jsdoc/reject-any-type
+/** @typedef {Record<string, (...args: any[]) => any>} EventMap */
+
+/**
+ * @template {EventMap} T
+ * @typedef {import("./DirectoryWatcher").Watcher<T>} Watcher
+ */
+
+/** @typedef {(item: string) => boolean} IgnoredFunction */
+/** @typedef {string[] | RegExp | string | IgnoredFunction} Ignored */
+
+/**
+ * @typedef {object} WatcherOptions
+ * @property {boolean=} followSymlinks true when need to resolve symlinks and watch symlink and real file, otherwise false
+ * @property {Ignored=} ignored ignore some files from watching (glob pattern or regexp)
+ * @property {number | boolean=} poll true when need to enable polling mode for watching, otherwise false
+ */
+
+/** @typedef {WatcherOptions & { aggregateTimeout?: number }} WatchOptions */
+
+/**
+ * @typedef {object} NormalizedWatchOptions
+ * @property {boolean} followSymlinks true when need to resolve symlinks and watch symlink and real file, otherwise false
+ * @property {IgnoredFunction} ignored ignore some files from watching (glob pattern or regexp)
+ * @property {number | boolean=} poll true when need to enable polling mode for watching, otherwise false
+ */
+
+/** @typedef {`scan (${string})` | "change" | "rename" | `watch ${string}` | `directory-removed ${string}`} EventType */
+/** @typedef {{ safeTime: number, timestamp: number, accuracy: number }} Entry */
+/** @typedef {{ safeTime: number }} OnlySafeTimeEntry */
+// eslint-disable-next-line jsdoc/ts-no-empty-object-type
+/** @typedef {{}} ExistanceOnlyTimeEntry */
+/** @typedef {Map<string, Entry | OnlySafeTimeEntry | ExistanceOnlyTimeEntry | null>} TimeInfoEntries */
+/** @typedef {Set<string>} Changes */
+/** @typedef {Set<string>} Removals */
+/** @typedef {{ changes: Changes, removals: Removals }} Aggregated */
+/** @typedef {{ files?: Iterable<string>, directories?: Iterable<string>, missing?: Iterable<string>, startTime?: number }} WatchMethodOptions */
+/** @typedef {Record<string, number>} Times */
+
+/**
+ * @param {MapIterator<WatchpackFileWatcher> | MapIterator<WatchpackDirectoryWatcher>} watchers watchers
+ * @param {Set<DirectoryWatcher>} set set
+ */
+function addWatchersToSet(watchers, set) {
+	for (const ww of watchers) {
+		const w = ww.watcher;
+		if (!set.has(w.directoryWatcher)) {
+			set.add(w.directoryWatcher);
+		}
+	}
+}
+
+/**
+ * @param {string} ignored ignored
+ * @returns {string | undefined} resolved global to regexp
+ */
+const stringToRegexp = (ignored) => {
+	if (ignored.length === 0) {
+		return;
+	}
+	const { source } = globToRegExp(ignored, { globstar: true, extended: true });
+	return `${source.slice(0, -1)}(?:$|\\/)`;
+};
+
+/**
+ * @param {Ignored=} ignored ignored
+ * @returns {(item: string) => boolean} ignored to function
+ */
+const ignoredToFunction = (ignored) => {
+	if (Array.isArray(ignored)) {
+		const stringRegexps = ignored.map((i) => stringToRegexp(i)).filter(Boolean);
+		if (stringRegexps.length === 0) {
+			return () => false;
+		}
+		const regexp = new RegExp(stringRegexps.join("|"));
+		return (item) => regexp.test(item.replace(/\\/g, "/"));
+	} else if (typeof ignored === "string") {
+		const stringRegexp = stringToRegexp(ignored);
+		if (!stringRegexp) {
+			return () => false;
+		}
+		const regexp = new RegExp(stringRegexp);
+		return (item) => regexp.test(item.replace(/\\/g, "/"));
+	} else if (ignored instanceof RegExp) {
+		return (item) => ignored.test(item.replace(/\\/g, "/"));
+	} else if (typeof ignored === "function") {
+		return ignored;
+	} else if (ignored) {
+		throw new Error(`Invalid option for 'ignored': ${ignored}`);
+	} else {
+		return () => false;
+	}
+};
+
+/**
+ * @param {WatchOptions} options options
+ * @returns {NormalizedWatchOptions} normalized options
+ */
+const normalizeOptions = (options) => ({
+	followSymlinks: Boolean(options.followSymlinks),
+	ignored: ignoredToFunction(options.ignored),
+	poll: options.poll,
+});
+
+const normalizeCache = new WeakMap();
+/**
+ * @param {WatchOptions} options options
+ * @returns {NormalizedWatchOptions} normalized options
+ */
+const cachedNormalizeOptions = (options) => {
+	const cacheEntry = normalizeCache.get(options);
+	if (cacheEntry !== undefined) return cacheEntry;
+	const normalized = normalizeOptions(options);
+	normalizeCache.set(options, normalized);
+	return normalized;
+};
+
+class WatchpackFileWatcher {
+	/**
+	 * @param {Watchpack} watchpack watchpack
+	 * @param {Watcher<FileWatcherEvents>} watcher watcher
+	 * @param {string | string[]} files files
+	 */
+	constructor(watchpack, watcher, files) {
+		/** @type {string[]} */
+		this.files = Array.isArray(files) ? files : [files];
+		this.watcher = watcher;
+		watcher.on("initial-missing", (type) => {
+			for (const file of this.files) {
+				if (!watchpack._missing.has(file)) {
+					watchpack._onRemove(file, file, type);
+				}
+			}
+		});
+		watcher.on("change", (mtime, type, _initial) => {
+			for (const file of this.files) {
+				watchpack._onChange(file, mtime, file, type);
+			}
+		});
+		watcher.on("remove", (type) => {
+			for (const file of this.files) {
+				watchpack._onRemove(file, file, type);
+			}
+		});
+	}
+
+	/**
+	 * @param {string | string[]} files files
+	 */
+	update(files) {
+		if (!Array.isArray(files)) {
+			if (this.files.length !== 1) {
+				this.files = [files];
+			} else if (this.files[0] !== files) {
+				this.files[0] = files;
+			}
+		} else {
+			this.files = files;
+		}
+	}
+
+	close() {
+		this.watcher.close();
+	}
+}
+
+class WatchpackDirectoryWatcher {
+	/**
+	 * @param {Watchpack} watchpack watchpack
+	 * @param {Watcher<DirectoryWatcherEvents>} watcher watcher
+	 * @param {string} directories directories
+	 */
+	constructor(watchpack, watcher, directories) {
+		/** @type {string[]} */
+		this.directories = Array.isArray(directories) ? directories : [directories];
+		this.watcher = watcher;
+		watcher.on("initial-missing", (type) => {
+			for (const item of this.directories) {
+				watchpack._onRemove(item, item, type);
+			}
+		});
+		watcher.on("change", (file, mtime, type, _initial) => {
+			for (const item of this.directories) {
+				watchpack._onChange(item, mtime, file, type);
+			}
+		});
+		watcher.on("remove", (type) => {
+			for (const item of this.directories) {
+				watchpack._onRemove(item, item, type);
+			}
+		});
+	}
+
+	/**
+	 * @param {string | string[]} directories directories
+	 */
+	update(directories) {
+		if (!Array.isArray(directories)) {
+			if (this.directories.length !== 1) {
+				this.directories = [directories];
+			} else if (this.directories[0] !== directories) {
+				this.directories[0] = directories;
+			}
+		} else {
+			this.directories = directories;
+		}
+	}
+
+	close() {
+		this.watcher.close();
+	}
+}
+
+/**
+ * @typedef {object} WatchpackEvents
+ * @property {(file: string, mtime: number, type: EventType) => void} change change event
+ * @property {(file: string, type: EventType) => void} remove remove event
+ * @property {(changes: Changes, removals: Removals) => void} aggregated aggregated event
+ */
+
+/**
+ * @extends {EventEmitter<{ [K in keyof WatchpackEvents]: Parameters<WatchpackEvents[K]> }>}
+ */
+class Watchpack extends EventEmitter {
+	/**
+	 * @param {WatchOptions=} options options
+	 */
+	constructor(options = {}) {
+		super();
+		if (!options) options = {};
+		/** @type {WatchOptions} */
+		this.options = options;
+		this.aggregateTimeout =
+			typeof options.aggregateTimeout === "number"
+				? options.aggregateTimeout
+				: 200;
+		/** @type {NormalizedWatchOptions} */
+		this.watcherOptions = cachedNormalizeOptions(options);
+		/** @type {WatcherManager} */
+		this.watcherManager = getWatcherManager(this.watcherOptions);
+		/** @type {Map<string, WatchpackFileWatcher>} */
+		this.fileWatchers = new Map();
+		/** @type {Map<string, WatchpackDirectoryWatcher>} */
+		this.directoryWatchers = new Map();
+		/** @type {Set<string>} */
+		this._missing = new Set();
+		this.startTime = undefined;
+		this.paused = false;
+		/** @type {Changes} */
+		this.aggregatedChanges = new Set();
+		/** @type {Removals} */
+		this.aggregatedRemovals = new Set();
+		/** @type {undefined | NodeJS.Timeout} */
+		this.aggregateTimer = undefined;
+		this._onTimeout = this._onTimeout.bind(this);
+	}
+
+	/**
+	 * @overload
+	 * @param {Iterable<string>} arg1 files
+	 * @param {Iterable<string>} arg2 directories
+	 * @param {number=} arg3 startTime
+	 * @returns {void}
+	 */
+	/**
+	 * @overload
+	 * @param {WatchMethodOptions} arg1 watch options
+	 * @returns {void}
+	 */
+	/**
+	 * @param {Iterable<string> | WatchMethodOptions} arg1 files
+	 * @param {Iterable<string>=} arg2 directories
+	 * @param {number=} arg3 startTime
+	 * @returns {void}
+	 */
+	watch(arg1, arg2, arg3) {
+		/** @type {Iterable<string> | undefined} */
+		let files;
+		/** @type {Iterable<string> | undefined} */
+		let directories;
+		/** @type {Iterable<string> | undefined} */
+		let missing;
+		/** @type {number | undefined} */
+		let startTime;
+		if (!arg2) {
+			({
+				files = [],
+				directories = [],
+				missing = [],
+				startTime,
+			} = /** @type {WatchMethodOptions} */ (arg1));
+		} else {
+			files = /** @type {Iterable<string>} */ (arg1);
+			directories = /** @type {Iterable<string>} */ (arg2);
+			missing = [];
+			startTime = /** @type {number} */ (arg3);
+		}
+		this.paused = false;
+		const { fileWatchers, directoryWatchers } = this;
+		const { ignored } = this.watcherOptions;
+		/**
+		 * @param {string} path path
+		 * @returns {boolean} true when need to filter, otherwise false
+		 */
+		const filter = (path) => !ignored(path);
+		/**
+		 * @template K, V
+		 * @param {Map<K, V | V[]>} map map
+		 * @param {K} key key
+		 * @param {V} item item
+		 */
+		const addToMap = (map, key, item) => {
+			const list = map.get(key);
+			if (list === undefined) {
+				map.set(key, item);
+			} else if (Array.isArray(list)) {
+				list.push(item);
+			} else {
+				map.set(key, [list, item]);
+			}
+		};
+		const fileWatchersNeeded = new Map();
+		const directoryWatchersNeeded = new Map();
+		/** @type {Set<string>} */
+		const missingFiles = new Set();
+		if (this.watcherOptions.followSymlinks) {
+			const resolver = new LinkResolver();
+			for (const file of files) {
+				if (filter(file)) {
+					for (const innerFile of resolver.resolve(file)) {
+						if (file === innerFile || filter(innerFile)) {
+							addToMap(fileWatchersNeeded, innerFile, file);
+						}
+					}
+				}
+			}
+			for (const file of missing) {
+				if (filter(file)) {
+					for (const innerFile of resolver.resolve(file)) {
+						if (file === innerFile || filter(innerFile)) {
+							missingFiles.add(file);
+							addToMap(fileWatchersNeeded, innerFile, file);
+						}
+					}
+				}
+			}
+			for (const dir of directories) {
+				if (filter(dir)) {
+					let first = true;
+					for (const innerItem of resolver.resolve(dir)) {
+						if (filter(innerItem)) {
+							addToMap(
+								first ? directoryWatchersNeeded : fileWatchersNeeded,
+								innerItem,
+								dir,
+							);
+						}
+						first = false;
+					}
+				}
+			}
+		} else {
+			for (const file of files) {
+				if (filter(file)) {
+					addToMap(fileWatchersNeeded, file, file);
+				}
+			}
+			for (const file of missing) {
+				if (filter(file)) {
+					missingFiles.add(file);
+					addToMap(fileWatchersNeeded, file, file);
+				}
+			}
+			for (const dir of directories) {
+				if (filter(dir)) {
+					addToMap(directoryWatchersNeeded, dir, dir);
+				}
+			}
+		}
+		// Close unneeded old watchers
+		// and update existing watchers
+		for (const [key, w] of fileWatchers) {
+			const needed = fileWatchersNeeded.get(key);
+			if (needed === undefined) {
+				w.close();
+				fileWatchers.delete(key);
+			} else {
+				w.update(needed);
+				fileWatchersNeeded.delete(key);
+			}
+		}
+		for (const [key, w] of directoryWatchers) {
+			const needed = directoryWatchersNeeded.get(key);
+			if (needed === undefined) {
+				w.close();
+				directoryWatchers.delete(key);
+			} else {
+				w.update(needed);
+				directoryWatchersNeeded.delete(key);
+			}
+		}
+		// Create new watchers and install handlers on these watchers
+		watchEventSource.batch(() => {
+			for (const [key, files] of fileWatchersNeeded) {
+				const watcher = this.watcherManager.watchFile(key, startTime);
+				if (watcher) {
+					fileWatchers.set(key, new WatchpackFileWatcher(this, watcher, files));
+				}
+			}
+			for (const [key, directories] of directoryWatchersNeeded) {
+				const watcher = this.watcherManager.watchDirectory(key, startTime);
+				if (watcher) {
+					directoryWatchers.set(
+						key,
+						new WatchpackDirectoryWatcher(this, watcher, directories),
+					);
+				}
+			}
+		});
+		this._missing = missingFiles;
+		this.startTime = startTime;
+	}
+
+	close() {
+		this.paused = true;
+		if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
+		for (const w of this.fileWatchers.values()) w.close();
+		for (const w of this.directoryWatchers.values()) w.close();
+		this.fileWatchers.clear();
+		this.directoryWatchers.clear();
+	}
+
+	pause() {
+		this.paused = true;
+		if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
+	}
+
+	/**
+	 * @returns {Record<string, number>} times
+	 */
+	getTimes() {
+		/** @type {Set<DirectoryWatcher>} */
+		const directoryWatchers = new Set();
+		addWatchersToSet(this.fileWatchers.values(), directoryWatchers);
+		addWatchersToSet(this.directoryWatchers.values(), directoryWatchers);
+		/** @type {Record<string, number>} */
+		const obj = Object.create(null);
+		for (const w of directoryWatchers) {
+			const times = w.getTimes();
+			for (const file of Object.keys(times)) obj[file] = times[file];
+		}
+		return obj;
+	}
+
+	/**
+	 * @returns {TimeInfoEntries} time info entries
+	 */
+	getTimeInfoEntries() {
+		/** @type {TimeInfoEntries} */
+		const map = new Map();
+		this.collectTimeInfoEntries(map, map);
+		return map;
+	}
+
+	/**
+	 * @param {TimeInfoEntries} fileTimestamps file timestamps
+	 * @param {TimeInfoEntries} directoryTimestamps directory timestamps
+	 */
+	collectTimeInfoEntries(fileTimestamps, directoryTimestamps) {
+		/** @type {Set<DirectoryWatcher>} */
+		const allWatchers = new Set();
+		addWatchersToSet(this.fileWatchers.values(), allWatchers);
+		addWatchersToSet(this.directoryWatchers.values(), allWatchers);
+		for (const w of allWatchers) {
+			w.collectTimeInfoEntries(fileTimestamps, directoryTimestamps);
+		}
+	}
+
+	/**
+	 * @returns {Aggregated} aggregated info
+	 */
+	getAggregated() {
+		if (this.aggregateTimer) {
+			clearTimeout(this.aggregateTimer);
+			this.aggregateTimer = undefined;
+		}
+		const changes = this.aggregatedChanges;
+		const removals = this.aggregatedRemovals;
+		this.aggregatedChanges = new Set();
+		this.aggregatedRemovals = new Set();
+		return { changes, removals };
+	}
+
+	/**
+	 * @param {string} item item
+	 * @param {number} mtime mtime
+	 * @param {string} file file
+	 * @param {EventType} type type
+	 */
+	_onChange(item, mtime, file, type) {
+		file = file || item;
+		if (!this.paused) {
+			this.emit("change", file, mtime, type);
+			if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
+			this.aggregateTimer = setTimeout(this._onTimeout, this.aggregateTimeout);
+		}
+		this.aggregatedRemovals.delete(item);
+		this.aggregatedChanges.add(item);
+	}
+
+	/**
+	 * @param {string} item item
+	 * @param {string} file file
+	 * @param {EventType} type type
+	 */
+	_onRemove(item, file, type) {
+		file = file || item;
+		if (!this.paused) {
+			this.emit("remove", file, type);
+			if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
+			this.aggregateTimer = setTimeout(this._onTimeout, this.aggregateTimeout);
+		}
+		this.aggregatedChanges.delete(item);
+		this.aggregatedRemovals.add(item);
+	}
+
+	_onTimeout() {
+		this.aggregateTimer = undefined;
+		const changes = this.aggregatedChanges;
+		const removals = this.aggregatedRemovals;
+		this.aggregatedChanges = new Set();
+		this.aggregatedRemovals = new Set();
+		this.emit("aggregated", changes, removals);
+	}
+}
+
+module.exports = Watchpack;

types/DirectoryWatcher.d.ts

+export = DirectoryWatcher;
+/** @typedef {Set<string>} InitialScanRemoved */
+/**
+ * @typedef {object} WatchpackEvents
+ * @property {(target: string, mtime: string, type: EventType, initial: boolean) => void} change change event
+ * @property {() => void} closed closed event
+ */
+/**
+ * @typedef {object} DirectoryWatcherOptions
+ * @property {boolean=} followSymlinks true when need to resolve symlinks and watch symlink and real file, otherwise false
+ * @property {IgnoredFunction=} ignored ignore some files from watching (glob pattern or regexp)
+ * @property {number | boolean=} poll true when need to enable polling mode for watching, otherwise false
+ */
+/**
+ * @extends {EventEmitter<{ [K in keyof WatchpackEvents]: Parameters<WatchpackEvents[K]> }>}
+ */
+declare class DirectoryWatcher extends EventEmitter<{
+	/**
+	 * change event
+	 */
+	change: [
+		target: string,
+		mtime: string,
+		type: import("./index").EventType,
+		initial: boolean,
+	];
+	/**
+	 * closed event
+	 */
+	closed: [];
+}> {
+	/**
+	 * @param {WatcherManager} watcherManager a watcher manager
+	 * @param {string} directoryPath directory path
+	 * @param {DirectoryWatcherOptions=} options options
+	 */
+	constructor(
+		watcherManager: WatcherManager,
+		directoryPath: string,
+		options?: DirectoryWatcherOptions | undefined,
+	);
+	watcherManager: import("./getWatcherManager").WatcherManager;
+	options: DirectoryWatcherOptions;
+	path: string;
+	/** @type {Map<string, Entry>} */
+	files: Map<string, Entry>;
+	/** @type {Map<string, number>} */
+	filesWithoutCase: Map<string, number>;
+	/** @type {Map<string, Watcher<DirectoryWatcherEvents> | boolean>} */
+	directories: Map<string, Watcher<DirectoryWatcherEvents> | boolean>;
+	lastWatchEvent: number;
+	initialScan: boolean;
+	ignored: import("./index").IgnoredFunction;
+	nestedWatching: boolean;
+	/** @type {number | false} */
+	polledWatching: number | false;
+	/** @type {undefined | NodeJS.Timeout} */
+	timeout: undefined | NodeJS.Timeout;
+	/** @type {null | InitialScanRemoved} */
+	initialScanRemoved: null | InitialScanRemoved;
+	/** @type {undefined | number} */
+	initialScanFinished: undefined | number;
+	/** @type {Map<string, Set<Watcher<DirectoryWatcherEvents> | Watcher<FileWatcherEvents>>>} */
+	watchers: Map<
+		string,
+		Set<Watcher<DirectoryWatcherEvents> | Watcher<FileWatcherEvents>>
+	>;
+	/** @type {Watcher<FileWatcherEvents> | null} */
+	parentWatcher: Watcher<FileWatcherEvents> | null;
+	refs: number;
+	/** @type {Map<string, boolean>} */
+	_activeEvents: Map<string, boolean>;
+	closed: boolean;
+	scanning: boolean;
+	scanAgain: boolean;
+	scanAgainInitial: boolean;
+	createWatcher(): void;
+	watcher: watchEventSource.Watcher | null | undefined;
+	/**
+	 * @template {(watcher: Watcher<EventMap>) => void} T
+	 * @param {string} path path
+	 * @param {T} fn function
+	 */
+	forEachWatcher<T extends (watcher: Watcher<EventMap>) => void>(
+		path: string,
+		fn: T,
+	): void;
+	/**
+	 * @param {string} itemPath an item path
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @param {EventType} type even type
+	 */
+	setMissing(itemPath: string, initial: boolean, type: EventType): void;
+	/**
+	 * @param {string} target a target to set file time
+	 * @param {number} mtime mtime
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @param {boolean} ignoreWhenEqual true to ignore when equal, otherwise false
+	 * @param {EventType} type type
+	 */
+	setFileTime(
+		target: string,
+		mtime: number,
+		initial: boolean,
+		ignoreWhenEqual: boolean,
+		type: EventType,
+	): void;
+	/**
+	 * @param {string} directoryPath directory path
+	 * @param {number} birthtime birthtime
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @param {EventType} type even type
+	 */
+	setDirectory(
+		directoryPath: string,
+		birthtime: number,
+		initial: boolean,
+		type: EventType,
+	): void;
+	/**
+	 * @param {string} directoryPath directory path
+	 */
+	createNestedWatcher(directoryPath: string): void;
+	/**
+	 * @param {boolean} flag true when nested, otherwise false
+	 */
+	setNestedWatching(flag: boolean): void;
+	/**
+	 * @param {string} target a target to watch
+	 * @param {number=} startTime start time
+	 * @returns {Watcher<DirectoryWatcherEvents> | Watcher<FileWatcherEvents>} watcher
+	 */
+	watch(
+		target: string,
+		startTime?: number | undefined,
+	): Watcher<DirectoryWatcherEvents> | Watcher<FileWatcherEvents>;
+	/**
+	 * @param {EventType} eventType event type
+	 * @param {string=} filename filename
+	 */
+	onWatchEvent(eventType: EventType, filename?: string | undefined): void;
+	/**
+	 * @param {unknown=} err error
+	 */
+	onWatcherError(err?: unknown | undefined): void;
+	/**
+	 * @param {Error | NodeJS.ErrnoException=} err error
+	 */
+	onStatsError(err?: (Error | NodeJS.ErrnoException) | undefined): void;
+	/**
+	 * @param {Error | NodeJS.ErrnoException=} err error
+	 */
+	onScanError(err?: (Error | NodeJS.ErrnoException) | undefined): void;
+	onScanFinished(): void;
+	/**
+	 * @param {string} reason a reason
+	 */
+	onDirectoryRemoved(reason: string): void;
+	watchInParentDirectory(): void;
+	/**
+	 * @param {boolean} initial true when initial, otherwise false
+	 */
+	doScan(initial: boolean): void;
+	/**
+	 * @returns {Record<string, number>} times
+	 */
+	getTimes(): Record<string, number>;
+	/**
+	 * @param {TimeInfoEntries} fileTimestamps file timestamps
+	 * @param {TimeInfoEntries} directoryTimestamps directory timestamps
+	 * @returns {number} safe time
+	 */
+	collectTimeInfoEntries(
+		fileTimestamps: TimeInfoEntries,
+		directoryTimestamps: TimeInfoEntries,
+	): number;
+	close(): void;
+}
+declare namespace DirectoryWatcher {
+	export {
+		EXISTANCE_ONLY_TIME_ENTRY,
+		Watcher,
+		IgnoredFunction,
+		EventType,
+		TimeInfoEntries,
+		Entry,
+		ExistanceOnlyTimeEntry,
+		OnlySafeTimeEntry,
+		EventMap,
+		WatcherManager,
+		EventSourceWatcher,
+		FileWatcherEvents,
+		DirectoryWatcherEvents,
+		InitialScanRemoved,
+		WatchpackEvents,
+		DirectoryWatcherOptions,
+	};
+}
+import { EventEmitter } from "events";
+/**
+ * @typedef {object} FileWatcherEvents
+ * @property {(type: EventType) => void} initial-missing initial missing event
+ * @property {(mtime: number, type: EventType, initial: boolean) => void} change change event
+ * @property {(type: EventType) => void} remove remove event
+ * @property {() => void} closed closed event
+ */
+/**
+ * @typedef {object} DirectoryWatcherEvents
+ * @property {(type: EventType) => void} initial-missing initial missing event
+ * @property {((file: string, mtime: number, type: EventType, initial: boolean) => void)} change change event
+ * @property {(type: EventType) => void} remove remove event
+ * @property {() => void} closed closed event
+ */
+/**
+ * @template {EventMap} T
+ * @extends {EventEmitter<{ [K in keyof T]: Parameters<T[K]> }>}
+ */
+declare class Watcher<T extends EventMap> extends EventEmitter<{
+	[K in keyof T]: Parameters<T[K]>;
+}> {
+	/**
+	 * @param {DirectoryWatcher} directoryWatcher a directory watcher
+	 * @param {string} target a target to watch
+	 * @param {number=} startTime start time
+	 */
+	constructor(
+		directoryWatcher: DirectoryWatcher,
+		target: string,
+		startTime?: number | undefined,
+	);
+	directoryWatcher: DirectoryWatcher;
+	path: string;
+	startTime: number | undefined;
+	/**
+	 * @param {number} mtime mtime
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @returns {boolean} true of start time less than mtile, otherwise false
+	 */
+	checkStartTime(mtime: number, initial: boolean): boolean;
+	close(): void;
+}
+import watchEventSource = require("./watchEventSource");
+/** @typedef {import("./index").IgnoredFunction} IgnoredFunction */
+/** @typedef {import("./index").EventType} EventType */
+/** @typedef {import("./index").TimeInfoEntries} TimeInfoEntries */
+/** @typedef {import("./index").Entry} Entry */
+/** @typedef {import("./index").ExistanceOnlyTimeEntry} ExistanceOnlyTimeEntry */
+/** @typedef {import("./index").OnlySafeTimeEntry} OnlySafeTimeEntry */
+/** @typedef {import("./index").EventMap} EventMap */
+/** @typedef {import("./getWatcherManager").WatcherManager} WatcherManager */
+/** @typedef {import("./watchEventSource").Watcher} EventSourceWatcher */
+/** @type {ExistanceOnlyTimeEntry} */
+declare const EXISTANCE_ONLY_TIME_ENTRY: ExistanceOnlyTimeEntry;
+type IgnoredFunction = import("./index").IgnoredFunction;
+type EventType = import("./index").EventType;
+type TimeInfoEntries = import("./index").TimeInfoEntries;
+type Entry = import("./index").Entry;
+type ExistanceOnlyTimeEntry = import("./index").ExistanceOnlyTimeEntry;
+type OnlySafeTimeEntry = import("./index").OnlySafeTimeEntry;
+type EventMap = import("./index").EventMap;
+type WatcherManager = import("./getWatcherManager").WatcherManager;
+type EventSourceWatcher = import("./watchEventSource").Watcher;
+type FileWatcherEvents = {
+	/**
+	 * initial missing event
+	 */
+	"initial-missing": (type: EventType) => void;
+	/**
+	 * change event
+	 */
+	change: (mtime: number, type: EventType, initial: boolean) => void;
+	/**
+	 * remove event
+	 */
+	remove: (type: EventType) => void;
+	/**
+	 * closed event
+	 */
+	closed: () => void;
+};
+type DirectoryWatcherEvents = {
+	/**
+	 * initial missing event
+	 */
+	"initial-missing": (type: EventType) => void;
+	/**
+	 * change event
+	 */
+	change: (
+		file: string,
+		mtime: number,
+		type: EventType,
+		initial: boolean,
+	) => void;
+	/**
+	 * remove event
+	 */
+	remove: (type: EventType) => void;
+	/**
+	 * closed event
+	 */
+	closed: () => void;
+};
+type InitialScanRemoved = Set<string>;
+type WatchpackEvents = {
+	/**
+	 * change event
+	 */
+	change: (
+		target: string,
+		mtime: string,
+		type: EventType,
+		initial: boolean,
+	) => void;
+	/**
+	 * closed event
+	 */
+	closed: () => void;
+};
+type DirectoryWatcherOptions = {
+	/**
+	 * true when need to resolve symlinks and watch symlink and real file, otherwise false
+	 */
+	followSymlinks?: boolean | undefined;
+	/**
+	 * ignore some files from watching (glob pattern or regexp)
+	 */
+	ignored?: IgnoredFunction | undefined;
+	/**
+	 * true when need to enable polling mode for watching, otherwise false
+	 */
+	poll?: (number | boolean) | undefined;
+};

types/getWatcherManager.d.ts

+declare namespace _exports {
+	export {
+		EventMap,
+		DirectoryWatcherOptions,
+		DirectoryWatcherEvents,
+		FileWatcherEvents,
+		Watcher,
+	};
+}
+declare function _exports(options: DirectoryWatcherOptions): WatcherManager;
+declare namespace _exports {
+	export { WatcherManager };
+}
+export = _exports;
+type EventMap = import("./index").EventMap;
+type DirectoryWatcherOptions =
+	import("./DirectoryWatcher").DirectoryWatcherOptions;
+type DirectoryWatcherEvents =
+	import("./DirectoryWatcher").DirectoryWatcherEvents;
+type FileWatcherEvents = import("./DirectoryWatcher").FileWatcherEvents;
+type Watcher<T extends EventMap> = import("./DirectoryWatcher").Watcher<T>;
+/** @typedef {import("./index").EventMap} EventMap */
+/** @typedef {import("./DirectoryWatcher").DirectoryWatcherOptions} DirectoryWatcherOptions */
+/** @typedef {import("./DirectoryWatcher").DirectoryWatcherEvents} DirectoryWatcherEvents */
+/** @typedef {import("./DirectoryWatcher").FileWatcherEvents} FileWatcherEvents */
+/**
+ * @template {EventMap} T
+ * @typedef {import("./DirectoryWatcher").Watcher<T>} Watcher
+ */
+declare class WatcherManager {
+	/**
+	 * @param {DirectoryWatcherOptions=} options options
+	 */
+	constructor(options?: DirectoryWatcherOptions | undefined);
+	options: DirectoryWatcher.DirectoryWatcherOptions;
+	/** @type {Map<string, DirectoryWatcher>} */
+	directoryWatchers: Map<string, DirectoryWatcher>;
+	/**
+	 * @param {string} directory a directory
+	 * @returns {DirectoryWatcher} a directory watcher
+	 */
+	getDirectoryWatcher(directory: string): DirectoryWatcher;
+	/**
+	 * @param {string} file file
+	 * @param {number=} startTime start time
+	 * @returns {Watcher<FileWatcherEvents> | null} watcher or null if file has no directory
+	 */
+	watchFile(
+		file: string,
+		startTime?: number | undefined,
+	): Watcher<FileWatcherEvents> | null;
+	/**
+	 * @param {string} directory directory
+	 * @param {number=} startTime start time
+	 * @returns {Watcher<DirectoryWatcherEvents>} watcher
+	 */
+	watchDirectory(
+		directory: string,
+		startTime?: number | undefined,
+	): Watcher<DirectoryWatcherEvents>;
+}
+import DirectoryWatcher = require("./DirectoryWatcher");

types/index.d.ts

+export = Watchpack;
+/**
+ * @typedef {object} WatchpackEvents
+ * @property {(file: string, mtime: number, type: EventType) => void} change change event
+ * @property {(file: string, type: EventType) => void} remove remove event
+ * @property {(changes: Changes, removals: Removals) => void} aggregated aggregated event
+ */
+/**
+ * @extends {EventEmitter<{ [K in keyof WatchpackEvents]: Parameters<WatchpackEvents[K]> }>}
+ */
+declare class Watchpack extends EventEmitter<{
+	/**
+	 * change event
+	 */
+	change: [file: string, mtime: number, type: EventType];
+	/**
+	 * remove event
+	 */
+	remove: [file: string, type: EventType];
+	/**
+	 * aggregated event
+	 */
+	aggregated: [changes: Changes, removals: Removals];
+}> {
+	/**
+	 * @param {WatchOptions=} options options
+	 */
+	constructor(options?: WatchOptions | undefined);
+	/** @type {WatchOptions} */
+	options: WatchOptions;
+	aggregateTimeout: number;
+	/** @type {NormalizedWatchOptions} */
+	watcherOptions: NormalizedWatchOptions;
+	/** @type {WatcherManager} */
+	watcherManager: WatcherManager;
+	/** @type {Map<string, WatchpackFileWatcher>} */
+	fileWatchers: Map<string, WatchpackFileWatcher>;
+	/** @type {Map<string, WatchpackDirectoryWatcher>} */
+	directoryWatchers: Map<string, WatchpackDirectoryWatcher>;
+	/** @type {Set<string>} */
+	_missing: Set<string>;
+	startTime: number | undefined;
+	paused: boolean;
+	/** @type {Changes} */
+	aggregatedChanges: Changes;
+	/** @type {Removals} */
+	aggregatedRemovals: Removals;
+	/** @type {undefined | NodeJS.Timeout} */
+	aggregateTimer: undefined | NodeJS.Timeout;
+	_onTimeout(): void;
+	/**
+	 * @overload
+	 * @param {Iterable<string>} arg1 files
+	 * @param {Iterable<string>} arg2 directories
+	 * @param {number=} arg3 startTime
+	 * @returns {void}
+	 */
+	watch(
+		arg1: Iterable<string>,
+		arg2: Iterable<string>,
+		arg3?: number | undefined,
+	): void;
+	/**
+	 * @overload
+	 * @param {WatchMethodOptions} arg1 watch options
+	 * @returns {void}
+	 */
+	watch(arg1: WatchMethodOptions): void;
+	close(): void;
+	pause(): void;
+	/**
+	 * @returns {Record<string, number>} times
+	 */
+	getTimes(): Record<string, number>;
+	/**
+	 * @returns {TimeInfoEntries} time info entries
+	 */
+	getTimeInfoEntries(): TimeInfoEntries;
+	/**
+	 * @param {TimeInfoEntries} fileTimestamps file timestamps
+	 * @param {TimeInfoEntries} directoryTimestamps directory timestamps
+	 */
+	collectTimeInfoEntries(
+		fileTimestamps: TimeInfoEntries,
+		directoryTimestamps: TimeInfoEntries,
+	): void;
+	/**
+	 * @returns {Aggregated} aggregated info
+	 */
+	getAggregated(): Aggregated;
+	/**
+	 * @param {string} item item
+	 * @param {number} mtime mtime
+	 * @param {string} file file
+	 * @param {EventType} type type
+	 */
+	_onChange(item: string, mtime: number, file: string, type: EventType): void;
+	/**
+	 * @param {string} item item
+	 * @param {string} file file
+	 * @param {EventType} type type
+	 */
+	_onRemove(item: string, file: string, type: EventType): void;
+}
+declare namespace Watchpack {
+	export {
+		WatcherManager,
+		DirectoryWatcher,
+		DirectoryWatcherEvents,
+		FileWatcherEvents,
+		EventMap,
+		Watcher,
+		IgnoredFunction,
+		Ignored,
+		WatcherOptions,
+		WatchOptions,
+		NormalizedWatchOptions,
+		EventType,
+		Entry,
+		OnlySafeTimeEntry,
+		ExistanceOnlyTimeEntry,
+		TimeInfoEntries,
+		Changes,
+		Removals,
+		Aggregated,
+		WatchMethodOptions,
+		Times,
+		WatchpackEvents,
+	};
+}
+import { EventEmitter } from "events";
+declare class WatchpackFileWatcher {
+	/**
+	 * @param {Watchpack} watchpack watchpack
+	 * @param {Watcher<FileWatcherEvents>} watcher watcher
+	 * @param {string | string[]} files files
+	 */
+	constructor(
+		watchpack: Watchpack,
+		watcher: Watcher<FileWatcherEvents>,
+		files: string | string[],
+	);
+	/** @type {string[]} */
+	files: string[];
+	watcher: import("./DirectoryWatcher").Watcher<
+		import("./DirectoryWatcher").FileWatcherEvents
+	>;
+	/**
+	 * @param {string | string[]} files files
+	 */
+	update(files: string | string[]): void;
+	close(): void;
+}
+declare class WatchpackDirectoryWatcher {
+	/**
+	 * @param {Watchpack} watchpack watchpack
+	 * @param {Watcher<DirectoryWatcherEvents>} watcher watcher
+	 * @param {string} directories directories
+	 */
+	constructor(
+		watchpack: Watchpack,
+		watcher: Watcher<DirectoryWatcherEvents>,
+		directories: string,
+	);
+	/** @type {string[]} */
+	directories: string[];
+	watcher: import("./DirectoryWatcher").Watcher<
+		import("./DirectoryWatcher").DirectoryWatcherEvents
+	>;
+	/**
+	 * @param {string | string[]} directories directories
+	 */
+	update(directories: string | string[]): void;
+	close(): void;
+}
+type WatcherManager = import("./getWatcherManager").WatcherManager;
+type DirectoryWatcher = import("./DirectoryWatcher");
+type DirectoryWatcherEvents =
+	import("./DirectoryWatcher").DirectoryWatcherEvents;
+type FileWatcherEvents = import("./DirectoryWatcher").FileWatcherEvents;
+type EventMap = Record<string, (...args: any[]) => any>;
+type Watcher<T extends EventMap> = import("./DirectoryWatcher").Watcher<T>;
+type IgnoredFunction = (item: string) => boolean;
+type Ignored = string[] | RegExp | string | IgnoredFunction;
+type WatcherOptions = {
+	/**
+	 * true when need to resolve symlinks and watch symlink and real file, otherwise false
+	 */
+	followSymlinks?: boolean | undefined;
+	/**
+	 * ignore some files from watching (glob pattern or regexp)
+	 */
+	ignored?: Ignored | undefined;
+	/**
+	 * true when need to enable polling mode for watching, otherwise false
+	 */
+	poll?: (number | boolean) | undefined;
+};
+type WatchOptions = WatcherOptions & {
+	aggregateTimeout?: number;
+};
+type NormalizedWatchOptions = {
+	/**
+	 * true when need to resolve symlinks and watch symlink and real file, otherwise false
+	 */
+	followSymlinks: boolean;
+	/**
+	 * ignore some files from watching (glob pattern or regexp)
+	 */
+	ignored: IgnoredFunction;
+	/**
+	 * true when need to enable polling mode for watching, otherwise false
+	 */
+	poll?: (number | boolean) | undefined;
+};
+type EventType =
+	| `scan (${string})`
+	| "change"
+	| "rename"
+	| `watch ${string}`
+	| `directory-removed ${string}`;
+type Entry = {
+	safeTime: number;
+	timestamp: number;
+	accuracy: number;
+};
+type OnlySafeTimeEntry = {
+	safeTime: number;
+};
+type ExistanceOnlyTimeEntry = {};
+type TimeInfoEntries = Map<
+	string,
+	Entry | OnlySafeTimeEntry | ExistanceOnlyTimeEntry | null
+>;
+type Changes = Set<string>;
+type Removals = Set<string>;
+type Aggregated = {
+	changes: Changes;
+	removals: Removals;
+};
+type WatchMethodOptions = {
+	files?: Iterable<string>;
+	directories?: Iterable<string>;
+	missing?: Iterable<string>;
+	startTime?: number;
+};
+type Times = Record<string, number>;
+type WatchpackEvents = {
+	/**
+	 * change event
+	 */
+	change: (file: string, mtime: number, type: EventType) => void;
+	/**
+	 * remove event
+	 */
+	remove: (file: string, type: EventType) => void;
+	/**
+	 * aggregated event
+	 */
+	aggregated: (changes: Changes, removals: Removals) => void;
+};

types/LinkResolver.d.ts

+export = LinkResolver;
+declare class LinkResolver {
+	/** @type {Map<string, readonly string[]>} */
+	cache: Map<string, readonly string[]>;
+	/**
+	 * @param {string} file path to file or directory
+	 * @returns {readonly string[]} array of file and all symlinks contributed in the resolving process (first item is the resolved file)
+	 */
+	resolve(file: string): readonly string[];
+}

types/reducePlan.d.ts

+declare namespace _exports {
+	export { TreeNode };
+}
+declare function _exports<T>(
+	plan: Map<string, T[] | T>,
+	limit: number,
+): Map<string, Map<T, string>>;
+export = _exports;
+type TreeNode<T> = {
+	/**
+	 * target
+	 */
+	target: string;
+	/**
+	 * parent
+	 */
+	parent: TreeNode<T>;
+	/**
+	 * children
+	 */
+	children: TreeNode<T>[];
+	/**
+	 * number of entries
+	 */
+	entries: number;
+	/**
+	 * true when active, otherwise false
+	 */
+	active: boolean;
+	/**
+	 * value
+	 */
+	value: T[] | T | undefined;
+};

types/watchEventSource.d.ts

+export function batch(fn: () => void): void;
+export function getNumberOfWatchers(): number;
+export function watch(filePath: string): Watcher;
+export type FSWatcher = import("fs").FSWatcher;
+export type EventType = import("./index").EventType;
+export type WatcherSet = Set<Watcher>;
+export type WatcherEvents = {
+	/**
+	 * change event
+	 */
+	change: (eventType: EventType, filename?: string) => void;
+	/**
+	 * error event
+	 */
+	error: (err: unknown) => void;
+};
+/**
+ * @typedef {object} WatcherEvents
+ * @property {(eventType: EventType, filename?: string) => void} change change event
+ * @property {(err: unknown) => void} error error event
+ */
+/**
+ * @extends {EventEmitter<{ [K in keyof WatcherEvents]: Parameters<WatcherEvents[K]> }>}
+ */
+export class Watcher extends EventEmitter<{
+	/**
+	 * change event
+	 */
+	change: [
+		eventType: import("./index").EventType,
+		filename?: string | undefined,
+	];
+	/**
+	 * error event
+	 */
+	error: [err: unknown];
+}> {
+	constructor();
+	close(): void;
+}
+/**
+ * @param {FSWatcher} watcher watcher
+ * @param {string} filePath a file path
+ * @param {(type: "rename" | "change", filename: string) => void} handleChangeEvent function to handle change
+ * @returns {(type: "rename" | "change", filename: string) => void} handler of change event
+ */
+export function createHandleChangeEvent(
+	watcher: FSWatcher,
+	filePath: string,
+	handleChangeEvent: (type: "rename" | "change", filename: string) => void,
+): (type: "rename" | "change", filename: string) => void;
+export const watcherLimit: number;
+import { EventEmitter } from "events";

types/watchpack.d.ts

+declare const _exports: typeof import("./index");
+export = _exports;

lib/DirectoryWatcher.js

@@ -7,8 +7,19 @@ /*
 
-const EventEmitter = require("events").EventEmitter;
+const { EventEmitter } = require("events");
+const path = require("path");
 const fs = require("graceful-fs");
-const path = require("path");
 
 const watchEventSource = require("./watchEventSource");
 
+/** @typedef {import("./index").IgnoredFunction} IgnoredFunction */
+/** @typedef {import("./index").EventType} EventType */
+/** @typedef {import("./index").TimeInfoEntries} TimeInfoEntries */
+/** @typedef {import("./index").Entry} Entry */
+/** @typedef {import("./index").ExistanceOnlyTimeEntry} ExistanceOnlyTimeEntry */
+/** @typedef {import("./index").OnlySafeTimeEntry} OnlySafeTimeEntry */
+/** @typedef {import("./index").EventMap} EventMap */
+/** @typedef {import("./getWatcherManager").WatcherManager} WatcherManager */
+/** @typedef {import("./watchEventSource").Watcher} EventSourceWatcher */
+
+/** @type {ExistanceOnlyTimeEntry} */
 const EXISTANCE_ONLY_TIME_ENTRY = Object.freeze({});
@@ -21,8 +32,13 @@
 
-const WATCHPACK_POLLING = process.env.WATCHPACK_POLLING;
+const { WATCHPACK_POLLING } = process.env;
 const FORCE_POLLING =
+	// @ts-expect-error avoid additional checks
 	`${+WATCHPACK_POLLING}` === WATCHPACK_POLLING
 		? +WATCHPACK_POLLING
-		: !!WATCHPACK_POLLING && WATCHPACK_POLLING !== "false";
+		: Boolean(WATCHPACK_POLLING) && WATCHPACK_POLLING !== "false";
 
+/**
+ * @param {string} str string
+ * @returns {string} lower cased string
+ */
 function withoutCase(str) {
@@ -32,4 +48,9 @@ return str.toLowerCase();
 
+/**
+ * @param {number} times times
+ * @param {() => void} callback callback
+ * @returns {() => void} result
+ */
 function needCalls(times, callback) {
-	return function() {
+	return function needCallsCallback() {
 		if (--times === 0) {
@@ -41,12 +62,63 @@ return callback();
 
+/**
+ * @param {Entry} entry entry
+ */
+function fixupEntryAccuracy(entry) {
+	if (entry.accuracy > FS_ACCURACY) {
+		entry.safeTime = entry.safeTime - entry.accuracy + FS_ACCURACY;
+		entry.accuracy = FS_ACCURACY;
+	}
+}
+
+/**
+ * @param {number=} mtime mtime
+ */
+function ensureFsAccuracy(mtime) {
+	if (!mtime) return;
+	if (FS_ACCURACY > 1 && mtime % 1 !== 0) FS_ACCURACY = 1;
+	else if (FS_ACCURACY > 10 && mtime % 10 !== 0) FS_ACCURACY = 10;
+	else if (FS_ACCURACY > 100 && mtime % 100 !== 0) FS_ACCURACY = 100;
+	else if (FS_ACCURACY > 1000 && mtime % 1000 !== 0) FS_ACCURACY = 1000;
+}
+
+/**
+ * @typedef {object} FileWatcherEvents
+ * @property {(type: EventType) => void} initial-missing initial missing event
+ * @property {(mtime: number, type: EventType, initial: boolean) => void} change change event
+ * @property {(type: EventType) => void} remove remove event
+ * @property {() => void} closed closed event
+ */
+
+/**
+ * @typedef {object} DirectoryWatcherEvents
+ * @property {(type: EventType) => void} initial-missing initial missing event
+ * @property {((file: string, mtime: number, type: EventType, initial: boolean) => void)} change change event
+ * @property {(type: EventType) => void} remove remove event
+ * @property {() => void} closed closed event
+ */
+
+/**
+ * @template {EventMap} T
+ * @extends {EventEmitter<{ [K in keyof T]: Parameters<T[K]> }>}
+ */
 class Watcher extends EventEmitter {
-	constructor(directoryWatcher, filePath, startTime) {
+	/**
+	 * @param {DirectoryWatcher} directoryWatcher a directory watcher
+	 * @param {string} target a target to watch
+	 * @param {number=} startTime start time
+	 */
+	constructor(directoryWatcher, target, startTime) {
 		super();
 		this.directoryWatcher = directoryWatcher;
-		this.path = filePath;
+		this.path = target;
 		this.startTime = startTime && +startTime;
 	}
 
+	/**
+	 * @param {number} mtime mtime
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @returns {boolean} true of start time less than mtile, otherwise false
+	 */
 	checkStartTime(mtime, initial) {
-		const startTime = this.startTime;
+		const { startTime } = this;
 		if (typeof startTime !== "number") return !initial;
@@ -57,2 +129,3 @@ return startTime <= mtime;
 	close() {
+		// @ts-expect-error bad typing in EventEmitter
 		this.emit("closed");
@@ -62,4 +135,27 @@ }
 
+/** @typedef {Set<string>} InitialScanRemoved */
+
+/**
+ * @typedef {object} WatchpackEvents
+ * @property {(target: string, mtime: string, type: EventType, initial: boolean) => void} change change event
+ * @property {() => void} closed closed event
+ */
+
+/**
+ * @typedef {object} DirectoryWatcherOptions
+ * @property {boolean=} followSymlinks true when need to resolve symlinks and watch symlink and real file, otherwise false
+ * @property {IgnoredFunction=} ignored ignore some files from watching (glob pattern or regexp)
+ * @property {number | boolean=} poll true when need to enable polling mode for watching, otherwise false
+ */
+
+/**
+ * @extends {EventEmitter<{ [K in keyof WatchpackEvents]: Parameters<WatchpackEvents[K]> }>}
+ */
 class DirectoryWatcher extends EventEmitter {
-	constructor(watcherManager, directoryPath, options) {
+	/**
+	 * @param {WatcherManager} watcherManager a watcher manager
+	 * @param {string} directoryPath directory path
+	 * @param {DirectoryWatcherOptions=} options options
+	 */
+	constructor(watcherManager, directoryPath, options = {}) {
 		super();
@@ -74,6 +170,7 @@ if (FORCE_POLLING) {
 		// timestamp is a value that should be compared with another timestamp (mtime)
-		/** @type {Map<string, { safeTime: number, timestamp: number }} */
+		/** @type {Map<string, Entry>} */
 		this.files = new Map();
 		/** @type {Map<string, number>} */
 		this.filesWithoutCase = new Map();
+		/** @type {Map<string, Watcher<DirectoryWatcherEvents> | boolean>} */
 		this.directories = new Map();
@@ -84,2 +181,3 @@ this.lastWatchEvent = 0;
 		this.nestedWatching = false;
+		/** @type {number | false} */
 		this.polledWatching =
@@ -89,11 +187,16 @@ typeof options.poll === "number"
 				: options.poll
-				? 5007
-				: false;
+					? 5007
+					: false;
+		/** @type {undefined | NodeJS.Timeout} */
 		this.timeout = undefined;
+		/** @type {null | InitialScanRemoved} */
 		this.initialScanRemoved = new Set();
+		/** @type {undefined | number} */
 		this.initialScanFinished = undefined;
-		/** @type {Map<string, Set<Watcher>>} */
+		/** @type {Map<string, Set<Watcher<DirectoryWatcherEvents> | Watcher<FileWatcherEvents>>>} */
 		this.watchers = new Map();
+		/** @type {Watcher<FileWatcherEvents> | null} */
 		this.parentWatcher = null;
 		this.refs = 0;
+		/** @type {Map<string, boolean>} */
 		this._activeEvents = new Map();
@@ -112,3 +215,4 @@ this.closed = false;
 			if (this.polledWatching) {
-				this.watcher = {
+				/** @type {EventSourceWatcher} */
+				(this.watcher) = /** @type {EventSourceWatcher} */ ({
 					close: () => {
@@ -119,4 +223,4 @@ if (this.timeout) {
 						}
-					}
-				};
+					},
+				});
 			} else {
@@ -126,3 +230,5 @@ if (IS_OSX) {
 				}
-				this.watcher = watchEventSource.watch(this.path);
+				this.watcher =
+					/** @type {EventSourceWatcher} */
+					(watchEventSource.watch(this.path));
 				this.watcher.on("change", this.onWatchEvent.bind(this));
@@ -136,2 +242,7 @@ this.watcher.on("error", this.onWatcherError.bind(this));
 
+	/**
+	 * @template {(watcher: Watcher<EventMap>) => void} T
+	 * @param {string} path path
+	 * @param {T} fn function
+	 */
 	forEachWatcher(path, fn) {
@@ -146,5 +257,11 @@ const watchers = this.watchers.get(withoutCase(path));
 
+	/**
+	 * @param {string} itemPath an item path
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @param {EventType} type even type
+	 */
 	setMissing(itemPath, initial, type) {
 		if (this.initialScan) {
-			this.initialScanRemoved.add(itemPath);
+			/** @type {InitialScanRemoved} */
+			(this.initialScanRemoved).add(itemPath);
 		}
@@ -154,9 +271,11 @@
 		if (oldDirectory) {
-			if (this.nestedWatching) oldDirectory.close();
+			if (this.nestedWatching) {
+				/** @type {Watcher<DirectoryWatcherEvents>} */
+				(oldDirectory).close();
+			}
 			this.directories.delete(itemPath);
-
-			this.forEachWatcher(itemPath, w => w.emit("remove", type));
+			this.forEachWatcher(itemPath, (w) => w.emit("remove", type));
 			if (!initial) {
-				this.forEachWatcher(this.path, w =>
-					w.emit("change", itemPath, null, type, initial)
+				this.forEachWatcher(this.path, (w) =>
+					w.emit("change", itemPath, null, type, initial),
 				);
@@ -170,6 +289,6 @@ }
 			const key = withoutCase(itemPath);
-			const count = this.filesWithoutCase.get(key) - 1;
+			const count = /** @type {number} */ (this.filesWithoutCase.get(key)) - 1;
 			if (count <= 0) {
 				this.filesWithoutCase.delete(key);
-				this.forEachWatcher(itemPath, w => w.emit("remove", type));
+				this.forEachWatcher(itemPath, (w) => w.emit("remove", type));
 			} else {
@@ -180,4 +299,4 @@ this.filesWithoutCase.set(key, count);
 			if (!initial) {
-				this.forEachWatcher(this.path, w =>
-					w.emit("change", itemPath, null, type, initial)
+				this.forEachWatcher(this.path, (w) =>
+					w.emit("change", itemPath, null, type, initial),
 				);
@@ -188,10 +307,18 @@ }
 
-	setFileTime(filePath, mtime, initial, ignoreWhenEqual, type) {
+	/**
+	 * @param {string} target a target to set file time
+	 * @param {number} mtime mtime
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @param {boolean} ignoreWhenEqual true to ignore when equal, otherwise false
+	 * @param {EventType} type type
+	 */
+	setFileTime(target, mtime, initial, ignoreWhenEqual, type) {
 		const now = Date.now();
 
-		if (this.ignored(filePath)) return;
+		if (this.ignored(target)) return;
 
-		const old = this.files.get(filePath);
+		const old = this.files.get(target);
 
-		let safeTime, accuracy;
+		let safeTime;
+		let accuracy;
 		if (initial) {
@@ -215,10 +342,10 @@ safeTime = Math.min(now, mtime) + FS_ACCURACY;
 
-		this.files.set(filePath, {
+		this.files.set(target, {
 			safeTime,
 			accuracy,
-			timestamp: mtime
+			timestamp: mtime,
 		});
 
 		if (!old) {
-			const key = withoutCase(filePath);
+			const key = withoutCase(target);
 			const count = this.filesWithoutCase.get(key);
@@ -235,3 +362,3 @@ this.filesWithoutCase.set(key, (count || 0) + 1);
 
-			this.forEachWatcher(filePath, w => {
+			this.forEachWatcher(target, (w) => {
 				if (!initial || w.checkStartTime(safeTime, initial)) {
@@ -242,7 +369,7 @@ w.emit("change", mtime, type);
 		} else if (!initial) {
-			this.forEachWatcher(filePath, w => w.emit("change", mtime, type));
+			this.forEachWatcher(target, (w) => w.emit("change", mtime, type));
 		}
-		this.forEachWatcher(this.path, w => {
+		this.forEachWatcher(this.path, (w) => {
 			if (!initial || w.checkStartTime(safeTime, initial)) {
-				w.emit("change", filePath, safeTime, type, initial);
+				w.emit("change", target, safeTime, type, initial);
 			}
@@ -252,2 +379,8 @@ });
 
+	/**
+	 * @param {string} directoryPath directory path
+	 * @param {number} birthtime birthtime
+	 * @param {boolean} initial true when initial, otherwise false
+	 * @param {EventType} type even type
+	 */
 	setDirectory(directoryPath, birthtime, initial, type) {
@@ -257,4 +390,4 @@ if (this.ignored(directoryPath)) return;
 			if (!initial) {
-				this.forEachWatcher(this.path, w =>
-					w.emit("change", directoryPath, birthtime, type, initial)
+				this.forEachWatcher(this.path, (w) =>
+					w.emit("change", directoryPath, birthtime, type, initial),
 				);
@@ -273,10 +406,5 @@ }
 
-				let safeTime;
-				if (initial) {
-					safeTime = Math.min(now, birthtime) + FS_ACCURACY;
-				} else {
-					safeTime = now;
-				}
+				const safeTime = initial ? Math.min(now, birthtime) + FS_ACCURACY : now;
 
-				this.forEachWatcher(directoryPath, w => {
+				this.forEachWatcher(directoryPath, (w) => {
 					if (!initial || w.checkStartTime(safeTime, false)) {
@@ -286,3 +414,3 @@ w.emit("change", birthtime, type);
 				});
-				this.forEachWatcher(this.path, w => {
+				this.forEachWatcher(this.path, (w) => {
 					if (!initial || w.checkStartTime(safeTime, initial)) {
@@ -296,8 +424,11 @@ w.emit("change", directoryPath, safeTime, type, initial);
 
+	/**
+	 * @param {string} directoryPath directory path
+	 */
 	createNestedWatcher(directoryPath) {
 		const watcher = this.watcherManager.watchDirectory(directoryPath, 1);
-		watcher.on("change", (filePath, mtime, type, initial) => {
-			this.forEachWatcher(this.path, w => {
+		watcher.on("change", (target, mtime, type, initial) => {
+			this.forEachWatcher(this.path, (w) => {
 				if (!initial || w.checkStartTime(mtime, initial)) {
-					w.emit("change", filePath, mtime, type, initial);
+					w.emit("change", target, mtime, type, initial);
 				}
@@ -309,5 +440,8 @@ });
 
+	/**
+	 * @param {boolean} flag true when nested, otherwise false
+	 */
 	setNestedWatching(flag) {
-		if (this.nestedWatching !== !!flag) {
-			this.nestedWatching = !!flag;
+		if (this.nestedWatching !== Boolean(flag)) {
+			this.nestedWatching = Boolean(flag);
 			if (this.nestedWatching) {
@@ -319,3 +453,4 @@ for (const directory of this.directories.keys()) {
 				for (const [directory, watcher] of this.directories) {
-					watcher.close();
+					/** @type {Watcher<DirectoryWatcherEvents>} */
+					(watcher).close();
 					this.directories.set(directory, true);
@@ -327,4 +462,9 @@ }
 
-	watch(filePath, startTime) {
-		const key = withoutCase(filePath);
+	/**
+	 * @param {string} target a target to watch
+	 * @param {number=} startTime start time
+	 * @returns {Watcher<DirectoryWatcherEvents> | Watcher<FileWatcherEvents>} watcher
+	 */
+	watch(target, startTime) {
+		const key = withoutCase(target);
 		let watchers = this.watchers.get(key);
@@ -336,3 +476,5 @@ if (watchers === undefined) {
 		this.refs++;
-		const watcher = new Watcher(this, filePath, startTime);
+		const watcher =
+			/** @type {Watcher<DirectoryWatcherEvents> | Watcher<FileWatcherEvents>} */
+			(new Watcher(this, target, startTime));
 		watcher.on("closed", () => {
@@ -346,3 +488,3 @@ if (--this.refs <= 0) {
 				this.watchers.delete(key);
-				if (this.path === filePath) this.setNestedWatching(false);
+				if (this.path === target) this.setNestedWatching(false);
 			}
@@ -352,3 +494,3 @@ });
 		let safeTime;
-		if (filePath === this.path) {
+		if (target === this.path) {
 			this.setNestedWatching(true);
@@ -361,3 +503,3 @@ safeTime = this.lastWatchEvent;
 		} else {
-			const entry = this.files.get(filePath);
+			const entry = this.files.get(target);
 			if (entry) {
@@ -371,19 +513,21 @@ fixupEntryAccuracy(entry);
 		if (safeTime) {
-			if (safeTime >= startTime) {
+			if (startTime && safeTime >= startTime) {
 				process.nextTick(() => {
 					if (this.closed) return;
-					if (filePath === this.path) {
-						watcher.emit(
+					if (target === this.path) {
+						/** @type {Watcher<DirectoryWatcherEvents>} */
+						(watcher).emit(
 							"change",
-							filePath,
+							target,
 							safeTime,
 							"watch (outdated on attach)",
-							true
+							true,
 						);
 					} else {
-						watcher.emit(
+						/** @type {Watcher<FileWatcherEvents>} */
+						(watcher).emit(
 							"change",
 							safeTime,
 							"watch (outdated on attach)",
-							true
+							true,
 						);
@@ -394,3 +538,6 @@ }
 		} else if (this.initialScan) {
-			if (this.initialScanRemoved.has(filePath)) {
+			if (
+				/** @type {InitialScanRemoved} */
+				(this.initialScanRemoved).has(target)
+			) {
 				process.nextTick(() => {
@@ -402,5 +549,9 @@ if (this.closed) return;
 		} else if (
-			filePath !== this.path &&
-			!this.directories.has(filePath) &&
-			watcher.checkStartTime(this.initialScanFinished, false)
+			target !== this.path &&
+			!this.directories.has(target) &&
+			watcher.checkStartTime(
+				/** @type {number} */
+				(this.initialScanFinished),
+				false,
+			)
 		) {
@@ -415,2 +566,6 @@ process.nextTick(() => {
 
+	/**
+	 * @param {EventType} eventType event type
+	 * @param {string=} filename filename
+	 */
 	onWatchEvent(eventType, filename) {
@@ -427,4 +582,4 @@ if (this.closed) return;
 
-		const filePath = path.join(this.path, filename);
-		if (this.ignored(filePath)) return;
+		const target = path.join(this.path, filename);
+		if (this.ignored(target)) return;
 
@@ -436,3 +591,3 @@ if (this._activeEvents.get(filename) === undefined) {
 				this._activeEvents.set(filename, false);
-				fs.lstat(filePath, (err, stats) => {
+				fs.lstat(target, (err, stats) => {
 					if (this.closed) return;
@@ -453,9 +608,7 @@ if (this._activeEvents.get(filename) === true) {
 							this.onStatsError(err);
-						} else {
-							if (filename === path.basename(this.path)) {
-								// This may indicate that the directory itself was removed
-								if (!fs.existsSync(this.path)) {
-									this.onDirectoryRemoved("stat failed");
-								}
-							}
+						} else if (
+							filename === path.basename(this.path) && // This may indicate that the directory itself was removed
+							!fs.existsSync(this.path)
+						) {
+							this.onDirectoryRemoved("stat failed");
 						}
@@ -465,20 +618,15 @@ }
 					if (!stats) {
-						this.setMissing(filePath, false, eventType);
+						this.setMissing(target, false, eventType);
 					} else if (stats.isDirectory()) {
-						this.setDirectory(
-							filePath,
-							+stats.birthtime || 1,
-							false,
-							eventType
-						);
+						this.setDirectory(target, +stats.birthtime || 1, false, eventType);
 					} else if (stats.isFile() || stats.isSymbolicLink()) {
 						if (stats.mtime) {
-							ensureFsAccuracy(stats.mtime);
+							ensureFsAccuracy(+stats.mtime);
 						}
 						this.setFileTime(
-							filePath,
+							target,
 							+stats.mtime || +stats.ctime || 1,
 							false,
 							false,
-							eventType
+							eventType,
 						);
@@ -494,7 +642,16 @@ }
 
+	/**
+	 * @param {unknown=} err error
+	 */
 	onWatcherError(err) {
 		if (this.closed) return;
 		if (err) {
-			if (err.code !== "EPERM" && err.code !== "ENOENT") {
-				console.error("Watchpack Error (watcher): " + err);
+			if (
+				/** @type {NodeJS.ErrnoException} */
+				(err).code !== "EPERM" &&
+				/** @type {NodeJS.ErrnoException} */
+				(err).code !== "ENOENT"
+			) {
+				// eslint-disable-next-line no-console
+				console.error(`Watchpack Error (watcher): ${err}`);
 			}
@@ -505,11 +662,19 @@ this.onDirectoryRemoved("watch error");
 
+	/**
+	 * @param {Error | NodeJS.ErrnoException=} err error
+	 */
 	onStatsError(err) {
 		if (err) {
-			console.error("Watchpack Error (stats): " + err);
+			// eslint-disable-next-line no-console
+			console.error(`Watchpack Error (stats): ${err}`);
 		}
 	}
 
+	/**
+	 * @param {Error | NodeJS.ErrnoException=} err error
+	 */
 	onScanError(err) {
 		if (err) {
-			console.error("Watchpack Error (initial scan): " + err);
+			// eslint-disable-next-line no-console
+			console.error(`Watchpack Error (initial scan): ${err}`);
 		}
@@ -528,2 +693,5 @@ this.onScanFinished();
 
+	/**
+	 * @param {string} reason a reason
+	 */
 	onDirectoryRemoved(reason) {
@@ -535,8 +703,8 @@ if (this.watcher) {
 		this.watchInParentDirectory();
-		const type = `directory-removed (${reason})`;
+		const type = /** @type {EventType} */ (`directory-removed (${reason})`);
 		for (const directory of this.directories.keys()) {
-			this.setMissing(directory, null, type);
+			this.setMissing(directory, false, type);
 		}
 		for (const file of this.files.keys()) {
-			this.setMissing(file, null, type);
+			this.setMissing(file, false, type);
 		}
@@ -553,3 +721,4 @@ }
 			this.parentWatcher = this.watcherManager.watchFile(this.path, 1);
-			this.parentWatcher.on("change", (mtime, type) => {
+			/** @type {Watcher<FileWatcherEvents>} */
+			(this.parentWatcher).on("change", (mtime, type) => {
 				if (this.closed) return;
@@ -569,8 +738,9 @@
 					// directory was created so we emit an event
-					this.forEachWatcher(this.path, w =>
-						w.emit("change", this.path, mtime, type, false)
+					this.forEachWatcher(this.path, (w) =>
+						w.emit("change", this.path, mtime, type, false),
 					);
 				}
 			});
-			this.parentWatcher.on("remove", () => {
+			/** @type {Watcher<FileWatcherEvents>} */
+			(this.parentWatcher).on("remove", () => {
 				this.onDirectoryRemoved("parent directory removed");
@@ -581,2 +751,5 @@ });
 
+	/**
+	 * @param {boolean} initial true when initial, otherwise false
+	 */
 	doScan(initial) {
@@ -615,3 +788,3 @@ if (this.scanning) {
 										"initial-missing",
-										"scan (parent directory missing in initial scan)"
+										"scan (parent directory missing in initial scan)",
 									);
@@ -631,3 +804,3 @@ }
 				const itemPaths = new Set(
-					items.map(item => path.join(this.path, item.normalize("NFC")))
+					items.map((item) => path.join(this.path, item.normalize("NFC"))),
 				);
@@ -666,3 +839,3 @@ for (const file of this.files.keys()) {
 										"initial-missing",
-										"scan (missing in initial scan)"
+										"scan (missing in initial scan)",
 									);
@@ -693,3 +866,3 @@ }
 							) {
-								this.setMissing(itemPath, initial, "scan (" + err2.code + ")");
+								this.setMissing(itemPath, initial, `scan (${err2.code})`);
 							} else {
@@ -703,3 +876,3 @@ this.onScanError(err2);
 							if (stats.mtime) {
-								ensureFsAccuracy(stats.mtime);
+								ensureFsAccuracy(+stats.mtime);
 							}
@@ -711,12 +884,14 @@ this.setFileTime(
 								true,
-								"scan (file)"
+								"scan (file)",
 							);
-						} else if (stats.isDirectory()) {
-							if (!initial || !this.directories.has(itemPath))
-								this.setDirectory(
-									itemPath,
-									+stats.birthtime || 1,
-									initial,
-									"scan (dir)"
-								);
+						} else if (
+							stats.isDirectory() &&
+							(!initial || !this.directories.has(itemPath))
+						) {
+							this.setDirectory(
+								itemPath,
+								+stats.birthtime || 1,
+								initial,
+								"scan (dir)",
+							);
 						}
@@ -731,2 +906,5 @@ itemFinished();
 
+	/**
+	 * @returns {Record<string, number>} times
+	 */
 	getTimes() {
@@ -742,3 +920,5 @@ const obj = Object.create(null);
 			for (const w of this.directories.values()) {
-				const times = w.directoryWatcher.getTimes();
+				const times =
+					/** @type {Watcher<DirectoryWatcherEvents>} */
+					(w).directoryWatcher.getTimes();
 				for (const file of Object.keys(times)) {
@@ -755,3 +935,3 @@ const time = times[file];
 				for (const watcher of watchers) {
-					const path = watcher.path;
+					const { path } = watcher;
 					if (!Object.prototype.hasOwnProperty.call(obj, path)) {
@@ -766,2 +946,7 @@ obj[path] = null;
 
+	/**
+	 * @param {TimeInfoEntries} fileTimestamps file timestamps
+	 * @param {TimeInfoEntries} directoryTimestamps directory timestamps
+	 * @returns {number} safe time
+	 */
 	collectTimeInfoEntries(fileTimestamps, directoryTimestamps) {
@@ -778,6 +963,7 @@ let safeTime = this.lastWatchEvent;
 					safeTime,
-					w.directoryWatcher.collectTimeInfoEntries(
+					/** @type {Watcher<DirectoryWatcherEvents>} */
+					(w).directoryWatcher.collectTimeInfoEntries(
 						fileTimestamps,
-						directoryTimestamps
-					)
+						directoryTimestamps,
+					),
 				);
@@ -787,3 +973,3 @@ }
 			directoryTimestamps.set(this.path, {
-				safeTime
+				safeTime,
 			});
@@ -795,4 +981,5 @@ } else {
 				fileTimestamps.set(dir, EXISTANCE_ONLY_TIME_ENTRY);
-				if (!directoryTimestamps.has(dir))
+				if (!directoryTimestamps.has(dir)) {
 					directoryTimestamps.set(dir, EXISTANCE_ONLY_TIME_ENTRY);
+				}
 			}
@@ -805,3 +992,3 @@ fileTimestamps.set(this.path, EXISTANCE_ONLY_TIME_ENTRY);
 				for (const watcher of watchers) {
-					const path = watcher.path;
+					const { path } = watcher;
 					if (!fileTimestamps.has(path)) {
@@ -825,3 +1012,4 @@ fileTimestamps.set(path, null);
 			for (const w of this.directories.values()) {
-				w.close();
+				/** @type {Watcher<DirectoryWatcherEvents>} */
+				(w).close();
 			}
@@ -840,16 +1028,2 @@ this.directories.clear();
 module.exports.EXISTANCE_ONLY_TIME_ENTRY = EXISTANCE_ONLY_TIME_ENTRY;
-
-function fixupEntryAccuracy(entry) {
-	if (entry.accuracy > FS_ACCURACY) {
-		entry.safeTime = entry.safeTime - entry.accuracy + FS_ACCURACY;
-		entry.accuracy = FS_ACCURACY;
-	}
-}
-
-function ensureFsAccuracy(mtime) {
-	if (!mtime) return;
-	if (FS_ACCURACY > 1 && mtime % 1 !== 0) FS_ACCURACY = 1;
-	else if (FS_ACCURACY > 10 && mtime % 10 !== 0) FS_ACCURACY = 10;
-	else if (FS_ACCURACY > 100 && mtime % 100 !== 0) FS_ACCURACY = 100;
-	else if (FS_ACCURACY > 1000 && mtime % 1000 !== 0) FS_ACCURACY = 1000;
-}
+module.exports.Watcher = Watcher;

lib/getWatcherManager.js

@@ -10,8 +10,25 @@ /*
 
+/** @typedef {import("./index").EventMap} EventMap */
+/** @typedef {import("./DirectoryWatcher").DirectoryWatcherOptions} DirectoryWatcherOptions */
+/** @typedef {import("./DirectoryWatcher").DirectoryWatcherEvents} DirectoryWatcherEvents */
+/** @typedef {import("./DirectoryWatcher").FileWatcherEvents} FileWatcherEvents */
+/**
+ * @template {EventMap} T
+ * @typedef {import("./DirectoryWatcher").Watcher<T>} Watcher
+ */
+
 class WatcherManager {
-	constructor(options) {
+	/**
+	 * @param {DirectoryWatcherOptions=} options options
+	 */
+	constructor(options = {}) {
 		this.options = options;
+		/** @type {Map<string, DirectoryWatcher>} */
 		this.directoryWatchers = new Map();
 	}
 
+	/**
+	 * @param {string} directory a directory
+	 * @returns {DirectoryWatcher} a directory watcher
+	 */
 	getDirectoryWatcher(directory) {
@@ -30,8 +47,18 @@ const watcher = this.directoryWatchers.get(directory);
 
-	watchFile(p, startTime) {
-		const directory = path.dirname(p);
-		if (directory === p) return null;
-		return this.getDirectoryWatcher(directory).watch(p, startTime);
+	/**
+	 * @param {string} file file
+	 * @param {number=} startTime start time
+	 * @returns {Watcher<FileWatcherEvents> | null} watcher or null if file has no directory
+	 */
+	watchFile(file, startTime) {
+		const directory = path.dirname(file);
+		if (directory === file) return null;
+		return this.getDirectoryWatcher(directory).watch(file, startTime);
 	}
 
+	/**
+	 * @param {string} directory directory
+	 * @param {number=} startTime start time
+	 * @returns {Watcher<DirectoryWatcherEvents>} watcher
+	 */
 	watchDirectory(directory, startTime) {
@@ -43,7 +70,8 @@ return this.getDirectoryWatcher(directory).watch(directory, startTime);
 const watcherManagers = new WeakMap();
+
 /**
- * @param {object} options options
+ * @param {DirectoryWatcherOptions} options options
  * @returns {WatcherManager} the watcher manager
  */
-module.exports = options => {
+module.exports = (options) => {
 	const watcherManager = watcherManagers.get(options);
@@ -50,0 +78,0 @@ if (watcherManager !== undefined) return watcherManager;

lib/LinkResolver.js

@@ -18,2 +18,3 @@ /*
 	constructor() {
+		/** @type {Map<string, readonly string[]>} */
 		this.cache = new Map();
@@ -24,3 +25,3 @@ }
 	 * @param {string} file path to file or directory
-	 * @returns {string[]} array of file and all symlinks contributed in the resolving process (first item is the resolved file)
+	 * @returns {readonly string[]} array of file and all symlinks contributed in the resolving process (first item is the resolved file)
 	 */
@@ -70,6 +71,7 @@ resolve(file) {
 				}
-				result = Object.freeze(Array.from(resultSet));
+				result = Object.freeze([...resultSet]);
 			} else if (parentResolved.length > 1) {
 				// we have links in the parent but not for the link content location
-				result = parentResolved.slice();
+				result = [...parentResolved];
+				// eslint-disable-next-line prefer-destructuring
 				result[0] = linkResolved[0];
@@ -81,3 +83,3 @@ // add the link
 				// we can return the link content location result
-				result = linkResolved.slice();
+				result = [...linkResolved];
 				// add the link
@@ -93,3 +95,3 @@ result.push(realFile);
 					// add the link
-					realFile
+					realFile,
 				]);
@@ -99,8 +101,12 @@ }
 			return result;
-		} catch (e) {
-			if (!EXPECTED_ERRORS.has(e.code)) {
-				throw e;
+		} catch (err) {
+			if (
+				/** @type {NodeJS.ErrnoException} */
+				(err).code &&
+				!EXPECTED_ERRORS.has(/** @type {NodeJS.ErrnoException} */ (err).code)
+			) {
+				throw err;
 			}
 			// no link
-			const result = parentResolved.slice();
+			const result = [...parentResolved];
 			result[0] = realFile;
@@ -113,2 +119,3 @@ Object.freeze(result);
 }
+
 module.exports = LinkResolver;

lib/reducePlan.js

@@ -11,9 +11,9 @@ /*
  * @template T
- * @typedef {Object} TreeNode
- * @property {string} filePath
- * @property {TreeNode} parent
- * @property {TreeNode[]} children
- * @property {number} entries
- * @property {boolean} active
- * @property {T[] | T | undefined} value
+ * @typedef {object} TreeNode
+ * @property {string} target target
+ * @property {TreeNode<T>} parent parent
+ * @property {TreeNode<T>[]} children children
+ * @property {number} entries number of entries
+ * @property {boolean} active true when active, otherwise false
+ * @property {T[] | T | undefined} value value
  */
@@ -23,4 +23,4 @@
  * @template T
- * @param {Map<string, T[] | T} plan
- * @param {number} limit
+ * @param {Map<string, T[] | T>} plan plan
+ * @param {number} limit limit
  * @returns {Map<string, Map<T, string>>} the new plan
@@ -31,5 +31,5 @@ */
 	// Convert to tree
-	for (const [filePath, value] of plan) {
-		treeMap.set(filePath, {
-			filePath,
+	for (const [target, value] of plan) {
+		treeMap.set(target, {
+			target,
 			parent: undefined,
@@ -39,3 +39,3 @@ children: undefined,
 			active: true,
-			value
+			value,
 		});
@@ -46,8 +46,8 @@ }
 	for (const node of treeMap.values()) {
-		const parentPath = path.dirname(node.filePath);
-		if (parentPath !== node.filePath) {
+		const parentPath = path.dirname(node.target);
+		if (parentPath !== node.target) {
 			let parent = treeMap.get(parentPath);
 			if (parent === undefined) {
 				parent = {
-					filePath: parentPath,
+					target: parentPath,
 					parent: undefined,
@@ -57,3 +57,3 @@ children: [node],
 					active: false,
-					value: undefined
+					value: undefined,
 				};
@@ -80,3 +80,3 @@ treeMap.set(parentPath, parent);
 		const overLimit = currentCount - limit;
-		let bestNode = undefined;
+		let bestNode;
 		let bestCost = Infinity;
@@ -105,3 +105,3 @@ for (const node of treeMap.values()) {
 		currentCount -= reduction;
-		let parent = bestNode.parent;
+		let { parent } = bestNode;
 		while (parent) {
@@ -131,6 +131,6 @@ parent.entries -= reduction;
 					for (const item of node.value) {
-						map.set(item, node.filePath);
+						map.set(item, node.target);
 					}
 				} else {
-					map.set(node.value, node.filePath);
+					map.set(node.value, node.target);
 				}
@@ -144,5 +144,5 @@ }
 		}
-		newPlan.set(rootNode.filePath, map);
+		newPlan.set(rootNode.target, map);
 	}
 	return newPlan;
 };

lib/watchEventSource.js

@@ -7,9 +7,13 @@ /*
 
+const { EventEmitter } = require("events");
 const fs = require("fs");
 const path = require("path");
-const { EventEmitter } = require("events");
 const reducePlan = require("./reducePlan");
 
+/** @typedef {import("fs").FSWatcher} FSWatcher */
+/** @typedef {import("./index").EventType} EventType */
+
 const IS_OSX = require("os").platform() === "darwin";
 const IS_WIN = require("os").platform() === "win32";
+
 const SUPPORTS_RECURSIVE_WATCHING = IS_OSX || IS_WIN;
@@ -20,6 +24,8 @@
 const watcherLimit =
+	// @ts-expect-error avoid additional checks
 	+process.env.WATCHPACK_WATCHER_LIMIT || (IS_OSX ? 20 : 10000);
 
-const recursiveWatcherLogging = !!process.env
-	.WATCHPACK_RECURSIVE_WATCHER_LOGGING;
+const recursiveWatcherLogging = Boolean(
+	process.env.WATCHPACK_RECURSIVE_WATCHER_LOGGING,
+);
 
@@ -41,4 +47,10 @@ let isBatch = false;
 
+/**
+ * @param {string} filePath file path
+ * @returns {NodeJS.ErrnoException} new error with file path in the message
+ */
 function createEPERMError(filePath) {
-	const error = new Error(`Operation not permitted: ${filePath}`);
+	const error =
+		/** @type {NodeJS.ErrnoException} */
+		(new Error(`Operation not permitted: ${filePath}`));
 	error.code = "EPERM";
@@ -48,2 +60,8 @@ return error;
 
+/**
+ * @param {FSWatcher} watcher watcher
+ * @param {string} filePath a file path
+ * @param {(type: "rename" | "change", filename: string) => void} handleChangeEvent function to handle change
+ * @returns {(type: "rename" | "change", filename: string) => void} handler of change event
+ */
 function createHandleChangeEvent(watcher, filePath, handleChangeEvent) {
@@ -71,5 +89,9 @@ return (type, filename) => {
 class DirectWatcher {
+	/**
+	 * @param {string} filePath file path
+	 */
 	constructor(filePath) {
 		this.filePath = filePath;
 		this.watchers = new Set();
+		/** @type {FSWatcher | undefined} */
 		this.watcher = undefined;
@@ -87,6 +109,6 @@ try {
 					}
-				}
+				},
 			);
 			watcher.on("change", handleChangeEvent);
-			watcher.on("error", error => {
+			watcher.on("error", (error) => {
 				for (const w of this.watchers) {
@@ -106,2 +128,5 @@ w.emit("error", error);
 
+	/**
+	 * @param {Watcher} watcher a watcher
+	 */
 	add(watcher) {
@@ -112,2 +137,5 @@ underlyingWatcher.set(watcher, this);
 
+	/**
+	 * @param {Watcher} watcher a watcher
+	 */
 	remove(watcher) {
@@ -127,3 +155,8 @@ this.watchers.delete(watcher);
 
+/** @typedef {Set<Watcher>} WatcherSet */
+
 class RecursiveWatcher {
+	/**
+	 * @param {string} rootPath a root path
+	 */
 	constructor(rootPath) {
@@ -133,3 +166,3 @@ this.rootPath = rootPath;
 		this.mapWatcherToPath = new Map();
-		/** @type {Map<string, Set<Watcher>>} */
+		/** @type {Map<string, WatcherSet>} */
 		this.mapPathToWatchers = new Map();
@@ -139,3 +172,3 @@ this.watcher = undefined;
 			const watcher = fs.watch(rootPath, {
-				recursive: true
+				recursive: true,
 			});
@@ -147,10 +180,10 @@ this.watcher = watcher;
 						process.stderr.write(
-							`[watchpack] dispatch ${type} event in recursive watcher (${this.rootPath}) to all watchers\n`
+							`[watchpack] dispatch ${type} event in recursive watcher (${this.rootPath}) to all watchers\n`,
 						);
 					}
 					for (const w of this.mapWatcherToPath.keys()) {
-						w.emit("change", type);
+						w.emit("change", /** @type {EventType} */ (type));
 					}
 				} else {
-					const dir = path.dirname(filename);
+					const dir = path.dirname(/** @type {string} */ (filename));
 					const watchers = this.mapPathToWatchers.get(dir);
@@ -163,3 +196,3 @@ if (recursiveWatcherLogging) {
 								watchers ? watchers.size : 0
-							} watchers\n`
+							} watchers\n`,
 						);
@@ -169,7 +202,11 @@ }
 					for (const w of watchers) {
-						w.emit("change", type, path.basename(filename));
+						w.emit(
+							"change",
+							/** @type {EventType} */ (type),
+							path.basename(/** @type {string} */ (filename)),
+						);
 					}
 				}
 			});
-			watcher.on("error", error => {
+			watcher.on("error", (error) => {
 				for (const w of this.mapWatcherToPath.keys()) {
@@ -189,3 +226,3 @@ w.emit("error", error);
 			process.stderr.write(
-				`[watchpack] created recursive watcher at ${rootPath}\n`
+				`[watchpack] created recursive watcher at ${rootPath}\n`,
 			);
@@ -195,2 +232,6 @@ }
 
+	/**
+	 * @param {string} filePath a file path
+	 * @param {Watcher} watcher a watcher
+	 */
 	add(filePath, watcher) {
@@ -210,2 +251,5 @@ underlyingWatcher.set(watcher, this);
 
+	/**
+	 * @param {Watcher} watcher a watcher
+	 */
 	remove(watcher) {
@@ -215,3 +259,3 @@ const subpath = this.mapWatcherToPath.get(watcher);
 		this.mapWatcherToPath.delete(watcher);
-		const set = this.mapPathToWatchers.get(subpath);
+		const set = /** @type {WatcherSet} */ (this.mapPathToWatchers.get(subpath));
 		set.delete(watcher);
@@ -227,3 +271,3 @@ if (set.size === 0) {
 				process.stderr.write(
-					`[watchpack] closed recursive watcher at ${this.rootPath}\n`
+					`[watchpack] closed recursive watcher at ${this.rootPath}\n`,
 				);
@@ -239,3 +283,16 @@ }
 
+/**
+ * @typedef {object} WatcherEvents
+ * @property {(eventType: EventType, filename?: string) => void} change change event
+ * @property {(err: unknown) => void} error error event
+ */
+
+/**
+ * @extends {EventEmitter<{ [K in keyof WatcherEvents]: Parameters<WatcherEvents[K]> }>}
+ */
 class Watcher extends EventEmitter {
+	constructor() {
+		super();
+	}
+
 	close() {
@@ -247,3 +304,4 @@ if (pendingWatchers.has(this)) {
 		const watcher = underlyingWatcher.get(this);
-		watcher.remove(this);
+		/** @type {RecursiveWatcher | DirectWatcher} */
+		(watcher).remove(this);
 		underlyingWatcher.delete(this);
@@ -253,3 +311,7 @@ }
 
-const createDirectWatcher = filePath => {
+/**
+ * @param {string} filePath a file path
+ * @returns {DirectWatcher} a directory watcher
+ */
+const createDirectWatcher = (filePath) => {
 	const existing = directWatchers.get(filePath);
@@ -262,3 +324,7 @@ if (existing !== undefined) return existing;
 
-const createRecursiveWatcher = rootPath => {
+/**
+ * @param {string} rootPath a root path
+ * @returns {RecursiveWatcher} a recursive watcher
+ */
+const createRecursiveWatcher = (rootPath) => {
 	const existing = recursiveWatchers.get(rootPath);
@@ -274,2 +340,6 @@ if (existing !== undefined) return existing;
 	const map = new Map();
+	/**
+	 * @param {Watcher} watcher a watcher
+	 * @param {string} filePath a file path
+	 */
 	const addWatcher = (watcher, filePath) => {
@@ -355,3 +425,26 @@ const entry = map.get(filePath);
 
-exports.watch = filePath => {
+module.exports.Watcher = Watcher;
+
+/**
+ * @param {() => void} fn a function
+ */
+module.exports.batch = (fn) => {
+	isBatch = true;
+	try {
+		fn();
+	} finally {
+		isBatch = false;
+		execute();
+	}
+};
+
+module.exports.createHandleChangeEvent = createHandleChangeEvent;
+
+module.exports.getNumberOfWatchers = () => watcherCount;
+
+/**
+ * @param {string} filePath a file path
+ * @returns {Watcher} watcher
+ */
+module.exports.watch = (filePath) => {
 	const watcher = new Watcher();
@@ -381,17 +474,2 @@ // Find an existing watcher
 
-exports.batch = fn => {
-	isBatch = true;
-	try {
-		fn();
-	} finally {
-		isBatch = false;
-		execute();
-	}
-};
-
-exports.getNumberOfWatchers = () => {
-	return watcherCount;
-};
-
-exports.createHandleChangeEvent = createHandleChangeEvent;
-exports.watcherLimit = watcherLimit;
+module.exports.watcherLimit = watcherLimit;

lib/watchpack.js

 /*
 	MIT License http://www.opensource.org/licenses/mit-license.php
-	Author Tobias Koppers @sokra
+	Author Alexander Akait @akexander-akait
 */
 "use strict";
 
-const getWatcherManager = require("./getWatcherManager");
-const LinkResolver = require("./LinkResolver");
-const EventEmitter = require("events").EventEmitter;
-const globToRegExp = require("glob-to-regexp");
-const watchEventSource = require("./watchEventSource");
-
-const EMPTY_ARRAY = [];
-const EMPTY_OPTIONS = {};
-
-function addWatchersToSet(watchers, set) {
-	for (const ww of watchers) {
-		const w = ww.watcher;
-		if (!set.has(w.directoryWatcher)) {
-			set.add(w.directoryWatcher);
-		}
-	}
-}
-
-const stringToRegexp = ignored => {
-	if (ignored.length === 0) {
-		return;
-	}
-	const source = globToRegExp(ignored, { globstar: true, extended: true })
-		.source;
-	return source.slice(0, source.length - 1) + "(?:$|\\/)";
-};
-
-const ignoredToFunction = ignored => {
-	if (Array.isArray(ignored)) {
-		const stringRegexps = ignored.map(i => stringToRegexp(i)).filter(Boolean);
-		if (stringRegexps.length === 0) {
-			return () => false;
-		}
-		const regexp = new RegExp(stringRegexps.join("|"));
-		return x => regexp.test(x.replace(/\\/g, "/"));
-	} else if (typeof ignored === "string") {
-		const stringRegexp = stringToRegexp(ignored);
-		if (!stringRegexp) {
-			return () => false;
-		}
-		const regexp = new RegExp(stringRegexp);
-		return x => regexp.test(x.replace(/\\/g, "/"));
-	} else if (ignored instanceof RegExp) {
-		return x => ignored.test(x.replace(/\\/g, "/"));
-	} else if (ignored instanceof Function) {
-		return ignored;
-	} else if (ignored) {
-		throw new Error(`Invalid option for 'ignored': ${ignored}`);
-	} else {
-		return () => false;
-	}
-};
-
-const normalizeOptions = options => {
-	return {
-		followSymlinks: !!options.followSymlinks,
-		ignored: ignoredToFunction(options.ignored),
-		poll: options.poll
-	};
-};
-
-const normalizeCache = new WeakMap();
-const cachedNormalizeOptions = options => {
-	const cacheEntry = normalizeCache.get(options);
-	if (cacheEntry !== undefined) return cacheEntry;
-	const normalized = normalizeOptions(options);
-	normalizeCache.set(options, normalized);
-	return normalized;
-};
-
-class WatchpackFileWatcher {
-	constructor(watchpack, watcher, files) {
-		this.files = Array.isArray(files) ? files : [files];
-		this.watcher = watcher;
-		watcher.on("initial-missing", type => {
-			for (const file of this.files) {
-				if (!watchpack._missing.has(file))
-					watchpack._onRemove(file, file, type);
-			}
-		});
-		watcher.on("change", (mtime, type) => {
-			for (const file of this.files) {
-				watchpack._onChange(file, mtime, file, type);
-			}
-		});
-		watcher.on("remove", type => {
-			for (const file of this.files) {
-				watchpack._onRemove(file, file, type);
-			}
-		});
-	}
-
-	update(files) {
-		if (!Array.isArray(files)) {
-			if (this.files.length !== 1) {
-				this.files = [files];
-			} else if (this.files[0] !== files) {
-				this.files[0] = files;
-			}
-		} else {
-			this.files = files;
-		}
-	}
-
-	close() {
-		this.watcher.close();
-	}
-}
-
-class WatchpackDirectoryWatcher {
-	constructor(watchpack, watcher, directories) {
-		this.directories = Array.isArray(directories) ? directories : [directories];
-		this.watcher = watcher;
-		watcher.on("initial-missing", type => {
-			for (const item of this.directories) {
-				watchpack._onRemove(item, item, type);
-			}
-		});
-		watcher.on("change", (file, mtime, type) => {
-			for (const item of this.directories) {
-				watchpack._onChange(item, mtime, file, type);
-			}
-		});
-		watcher.on("remove", type => {
-			for (const item of this.directories) {
-				watchpack._onRemove(item, item, type);
-			}
-		});
-	}
-
-	update(directories) {
-		if (!Array.isArray(directories)) {
-			if (this.directories.length !== 1) {
-				this.directories = [directories];
-			} else if (this.directories[0] !== directories) {
-				this.directories[0] = directories;
-			}
-		} else {
-			this.directories = directories;
-		}
-	}
-
-	close() {
-		this.watcher.close();
-	}
-}
-
-class Watchpack extends EventEmitter {
-	constructor(options) {
-		super();
-		if (!options) options = EMPTY_OPTIONS;
-		this.options = options;
-		this.aggregateTimeout =
-			typeof options.aggregateTimeout === "number"
-				? options.aggregateTimeout
-				: 200;
-		this.watcherOptions = cachedNormalizeOptions(options);
-		this.watcherManager = getWatcherManager(this.watcherOptions);
-		this.fileWatchers = new Map();
-		this.directoryWatchers = new Map();
-		this._missing = new Set();
-		this.startTime = undefined;
-		this.paused = false;
-		this.aggregatedChanges = new Set();
-		this.aggregatedRemovals = new Set();
-		this.aggregateTimer = undefined;
-		this._onTimeout = this._onTimeout.bind(this);
-	}
-
-	watch(arg1, arg2, arg3) {
-		let files, directories, missing, startTime;
-		if (!arg2) {
-			({
-				files = EMPTY_ARRAY,
-				directories = EMPTY_ARRAY,
-				missing = EMPTY_ARRAY,
-				startTime
-			} = arg1);
-		} else {
-			files = arg1;
-			directories = arg2;
-			missing = EMPTY_ARRAY;
-			startTime = arg3;
-		}
-		this.paused = false;
-		const fileWatchers = this.fileWatchers;
-		const directoryWatchers = this.directoryWatchers;
-		const ignored = this.watcherOptions.ignored;
-		const filter = path => !ignored(path);
-		const addToMap = (map, key, item) => {
-			const list = map.get(key);
-			if (list === undefined) {
-				map.set(key, item);
-			} else if (Array.isArray(list)) {
-				list.push(item);
-			} else {
-				map.set(key, [list, item]);
-			}
-		};
-		const fileWatchersNeeded = new Map();
-		const directoryWatchersNeeded = new Map();
-		const missingFiles = new Set();
-		if (this.watcherOptions.followSymlinks) {
-			const resolver = new LinkResolver();
-			for (const file of files) {
-				if (filter(file)) {
-					for (const innerFile of resolver.resolve(file)) {
-						if (file === innerFile || filter(innerFile)) {
-							addToMap(fileWatchersNeeded, innerFile, file);
-						}
-					}
-				}
-			}
-			for (const file of missing) {
-				if (filter(file)) {
-					for (const innerFile of resolver.resolve(file)) {
-						if (file === innerFile || filter(innerFile)) {
-							missingFiles.add(file);
-							addToMap(fileWatchersNeeded, innerFile, file);
-						}
-					}
-				}
-			}
-			for (const dir of directories) {
-				if (filter(dir)) {
-					let first = true;
-					for (const innerItem of resolver.resolve(dir)) {
-						if (filter(innerItem)) {
-							addToMap(
-								first ? directoryWatchersNeeded : fileWatchersNeeded,
-								innerItem,
-								dir
-							);
-						}
-						first = false;
-					}
-				}
-			}
-		} else {
-			for (const file of files) {
-				if (filter(file)) {
-					addToMap(fileWatchersNeeded, file, file);
-				}
-			}
-			for (const file of missing) {
-				if (filter(file)) {
-					missingFiles.add(file);
-					addToMap(fileWatchersNeeded, file, file);
-				}
-			}
-			for (const dir of directories) {
-				if (filter(dir)) {
-					addToMap(directoryWatchersNeeded, dir, dir);
-				}
-			}
-		}
-		// Close unneeded old watchers
-		// and update existing watchers
-		for (const [key, w] of fileWatchers) {
-			const needed = fileWatchersNeeded.get(key);
-			if (needed === undefined) {
-				w.close();
-				fileWatchers.delete(key);
-			} else {
-				w.update(needed);
-				fileWatchersNeeded.delete(key);
-			}
-		}
-		for (const [key, w] of directoryWatchers) {
-			const needed = directoryWatchersNeeded.get(key);
-			if (needed === undefined) {
-				w.close();
-				directoryWatchers.delete(key);
-			} else {
-				w.update(needed);
-				directoryWatchersNeeded.delete(key);
-			}
-		}
-		// Create new watchers and install handlers on these watchers
-		watchEventSource.batch(() => {
-			for (const [key, files] of fileWatchersNeeded) {
-				const watcher = this.watcherManager.watchFile(key, startTime);
-				if (watcher) {
-					fileWatchers.set(key, new WatchpackFileWatcher(this, watcher, files));
-				}
-			}
-			for (const [key, directories] of directoryWatchersNeeded) {
-				const watcher = this.watcherManager.watchDirectory(key, startTime);
-				if (watcher) {
-					directoryWatchers.set(
-						key,
-						new WatchpackDirectoryWatcher(this, watcher, directories)
-					);
-				}
-			}
-		});
-		this._missing = missingFiles;
-		this.startTime = startTime;
-	}
-
-	close() {
-		this.paused = true;
-		if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
-		for (const w of this.fileWatchers.values()) w.close();
-		for (const w of this.directoryWatchers.values()) w.close();
-		this.fileWatchers.clear();
-		this.directoryWatchers.clear();
-	}
-
-	pause() {
-		this.paused = true;
-		if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
-	}
-
-	getTimes() {
-		const directoryWatchers = new Set();
-		addWatchersToSet(this.fileWatchers.values(), directoryWatchers);
-		addWatchersToSet(this.directoryWatchers.values(), directoryWatchers);
-		const obj = Object.create(null);
-		for (const w of directoryWatchers) {
-			const times = w.getTimes();
-			for (const file of Object.keys(times)) obj[file] = times[file];
-		}
-		return obj;
-	}
-
-	getTimeInfoEntries() {
-		const map = new Map();
-		this.collectTimeInfoEntries(map, map);
-		return map;
-	}
-
-	collectTimeInfoEntries(fileTimestamps, directoryTimestamps) {
-		const allWatchers = new Set();
-		addWatchersToSet(this.fileWatchers.values(), allWatchers);
-		addWatchersToSet(this.directoryWatchers.values(), allWatchers);
-		const safeTime = { value: 0 };
-		for (const w of allWatchers) {
-			w.collectTimeInfoEntries(fileTimestamps, directoryTimestamps, safeTime);
-		}
-	}
-
-	getAggregated() {
-		if (this.aggregateTimer) {
-			clearTimeout(this.aggregateTimer);
-			this.aggregateTimer = undefined;
-		}
-		const changes = this.aggregatedChanges;
-		const removals = this.aggregatedRemovals;
-		this.aggregatedChanges = new Set();
-		this.aggregatedRemovals = new Set();
-		return { changes, removals };
-	}
-
-	_onChange(item, mtime, file, type) {
-		file = file || item;
-		if (!this.paused) {
-			this.emit("change", file, mtime, type);
-			if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
-			this.aggregateTimer = setTimeout(this._onTimeout, this.aggregateTimeout);
-		}
-		this.aggregatedRemovals.delete(item);
-		this.aggregatedChanges.add(item);
-	}
-
-	_onRemove(item, file, type) {
-		file = file || item;
-		if (!this.paused) {
-			this.emit("remove", file, type);
-			if (this.aggregateTimer) clearTimeout(this.aggregateTimer);
-			this.aggregateTimer = setTimeout(this._onTimeout, this.aggregateTimeout);
-		}
-		this.aggregatedChanges.delete(item);
-		this.aggregatedRemovals.add(item);
-	}
-
-	_onTimeout() {
-		this.aggregateTimer = undefined;
-		const changes = this.aggregatedChanges;
-		const removals = this.aggregatedRemovals;
-		this.aggregatedChanges = new Set();
-		this.aggregatedRemovals = new Set();
-		this.emit("aggregated", changes, removals);
-	}
-}
-
-module.exports = Watchpack;
+// TODO remove this file in the next major release
+module.exports = require("./index");

package.json

 {
   "name": "watchpack",
-  "version": "2.4.4",
+  "version": "2.5.0",
   "description": "",
-  "main": "./lib/watchpack.js",
+  "homepage": "https://github.com/webpack/watchpack",
+  "bugs": {
+    "url": "https://github.com/webpack/watchpack/issues"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/webpack/watchpack.git"
+  },
+  "license": "MIT",
+  "author": "Tobias Koppers @sokra",
+  "main": "lib/index.js",
+  "types": "types/index.js",
   "directories": {
@@ -10,38 +21,52 @@ "test": "test"
   "files": [
-    "lib/"
+    "lib/",
+    "types/"
   ],
   "scripts": {
-    "pretty-files": "prettier \"lib/**.*\" \"test/**/*.js\" --write",
-    "lint": "eslint lib",
-    "test:only": "mocha",
-    "test:coverage": "istanbul cover node_modules/mocha/bin/_mocha",
-    "pretest": "yarn lint",
-    "test": "mocha"
+    "lint": "npm run lint:code && npm run lint:types && npm run lint:types-test && npm run lint:declarations && npm run fmt:check",
+    "lint:code": "eslint --cache .",
+    "lint:types": "tsc",
+    "lint:types-test": "tsc -p tsconfig.types.test.json",
+    "lint:declarations": "npm run fix:declarations && git diff --exit-code ./types",
+    "fix": "npm run fix:code && npm run fix:declarations",
+    "fix:code": "npm run lint:code -- --fix",
+    "fix:declarations": "tsc --noEmit false --declaration --emitDeclarationOnly --outDir types && npm run fmt -- ./types",
+    "fmt": "npm run fmt:base -- --log-level warn --write",
+    "fmt:check": "npm run fmt:base -- --check",
+    "fmt:base": "prettier --cache --ignore-unknown .",
+    "pretest": "npm run lint",
+    "test": "npm run test:coverage",
+    "test:base": "jest --runInBand",
+    "test:only": "npm run test:base",
+    "test:watch": "npm run test:base -- --watch",
+    "test:coverage": "npm run test:base -- --collectCoverageFrom=\"lib/**/*.js\" --coverage"
   },
-  "repository": {
-    "type": "git",
-    "url": "https://github.com/webpack/watchpack.git"
+  "dependencies": {
+    "glob-to-regexp": "^0.4.1",
+    "graceful-fs": "^4.1.2"
   },
-  "author": "Tobias Koppers @sokra",
-  "license": "MIT",
-  "bugs": {
-    "url": "https://github.com/webpack/watchpack/issues"
-  },
-  "homepage": "https://github.com/webpack/watchpack",
   "devDependencies": {
-    "coveralls": "^3.0.0",
-    "eslint": "^5.11.1",
-    "eslint-config-prettier": "^4.3.0",
-    "eslint-plugin-prettier": "^3.1.0",
-    "istanbul": "^0.4.3",
-    "mocha": "^5.0.1",
-    "prettier": "^1.11.0",
+    "@eslint/js": "^9.28.0",
+    "@eslint/markdown": "^7.5.1",
+    "@stylistic/eslint-plugin": "^5.6.1",
+    "@types/glob-to-regexp": "^0.4.4",
+    "@types/graceful-fs": "^4.1.9",
+    "@types/jest": "^27.5.1",
+    "@types/node": "^24.10.4",
+    "eslint": "^9.39.2",
+    "eslint-config-prettier": "^10.1.8",
+    "eslint-config-webpack": "^4.7.3",
+    "eslint-plugin-import": "^2.32.0",
+    "eslint-plugin-jest": "^29.5.0",
+    "eslint-plugin-jsdoc": "^61.5.0",
+    "eslint-plugin-n": "^17.23.1",
+    "eslint-plugin-prettier": "^5.5.4",
+    "eslint-plugin-unicorn": "^62.0.0",
+    "globals": "^16.5.0",
+    "jest": "^27.5.1",
+    "prettier": "^3.7.4",
     "rimraf": "^2.6.2",
-    "should": "^8.3.1",
+    "typescript": "^5.9.3",
     "write-file-atomic": "^3.0.1"
   },
-  "dependencies": {
-    "glob-to-regexp": "^0.4.1",
-    "graceful-fs": "^4.1.2"
-  },
   "engines": {
@@ -48,0 +73,0 @@ "node": ">=10.13.0"

README.md

@@ -24,5 +24,5 @@ # watchpack
 ```javascript
-var Watchpack = require("watchpack");
+const Watchpack = require("watchpack");
 
-var wp = new Watchpack({
+const wp = new Watchpack({
 	// options:
@@ -46,3 +46,3 @@ aggregateTimeout: 1000,
 
-	ignored: "**/.git"
+	ignored: "**/.git",
 	// ignored: "string" - a glob pattern for files or folders that should not be watched
@@ -66,3 +66,3 @@ // ignored: ["string", "string"] - multiple glob patterns that should be ignored
 	missing: listOfNotExistingItems,
-	startTime: Date.now() - 10000
+	startTime: Date.now() - 10000,
 });
@@ -82,3 +82,3 @@ // starts watching these files and directories
 
-wp.on("change", function(filePath, mtime, explanation) {
+wp.on("change", (filePath, mtime, explanation) => {
 	// filePath: the changed file
@@ -89,3 +89,3 @@ // mtime: last modified time for the changed file
 
-wp.on("remove", function(filePath, explanation) {
+wp.on("remove", (filePath, explanation) => {
 	// filePath: the removed file or directory
@@ -95,3 +95,3 @@ // explanation: textual information how this change was detected
 
-wp.on("aggregated", function(changes, removals) {
+wp.on("aggregated", (changes, removals) => {
 	// changes: a Set of all changed files
@@ -129,3 +129,3 @@ // removals: a Set of all removed files
 // Watchpack.prototype.getTimeInfoEntries()
-var fileTimes = wp.getTimeInfoEntries();
+const fileTimes = wp.getTimeInfoEntries();
 // returns a Map with all known time info objects for files and directories
@@ -136,3 +136,3 @@ // similar to collectTimeInfoEntries but returns a single map with all entries
 // Watchpack.prototype.getTimes()
-var fileTimes = wp.getTimes();
+const fileTimesOld = wp.getTimes();
 // returns an object with all known change times for files
@@ -139,0 +139,0 @@ // this include timestamps from files not directly watched

New alerts

Major refactor

Supply chain risk

Package has recently undergone a major refactor. It may be unstable or indicate significant internal changes. Use caution when updating to versions that include significant changes.

Found 1 instance in 1 package

Environment variable access

Supply chain risk

Package accesses environment variables, which may be a sign of credential stuffing or data theft.

Found 1 instance in 1 package

Fixed alerts

Environment variable access

Supply chain risk

Package accesses environment variables, which may be a sign of credential stuffing or data theft.

Found 1 instance in 1 package

Improved metrics

Total package byte prevSize

95722

66.01%

Number of package files

17

88.89%

Lines of code

2909

68.93%

Worsened metrics

Dev dependency count

22

120%

Number of medium supply chain risk alerts

1

Infinity%

No dependency changes