astro/dist/content/watcher.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

// This lets us use the standard Vite FSWatcher, but also track all listeners added by the content loaders
// We do this so we can remove them all when we re-sync.
export function createWatcherWrapper(watcher) {
	const listeners = new Map();
	const handler = { get(target, prop, receiver) {
		// Intercept the 'on' method and track the listener
		if (prop === "on") {
			return function(event, callback) {
				if (!listeners.has(event)) {
					listeners.set(event, new Set());
				}
				// Track the listener
				listeners.get(event).add(callback);
				// Call the original method
				return Reflect.get(target, prop, receiver).call(target, event, callback);
			};
		}
		// Intercept the 'off' method
		if (prop === "off") {
			return function(event, callback) {
				// Remove from our tracking
				listeners.get(event)?.delete(callback);
				// Call the original method
				return Reflect.get(target, prop, receiver).call(target, event, callback);
			};
		}
		// Adds a function to remove all listeners added by us
		if (prop === "removeAllTrackedListeners") {
			return function() {
				for (const [event, callbacks] of listeners.entries()) {
					for (const callback of callbacks) {
						target.off(event, callback);
					}
					callbacks.clear();
				}
				listeners.clear();
			};
		}
		// Return original method/property for everything else
		return Reflect.get(target, prop, receiver);
	} };
	return new Proxy(watcher, handler);
}