@stainless-code/persist/dist/transport/crosstab.mjs

Hydration-aware persistence for any reactive store — zero-dep persistSource core; codecs, backends, cross-tab transport, source + framework hydration adapters ship as opt-in recipes

//#region src/adapters/transport/crosstab.ts
/**
* Bridge a `BroadcastChannel` as the cross-tab transport for backends that
* fire no `storage` events (IndexedDB). Posts `storageArea: null` on every
* event so key-only matching applies in every tab (each tab owns its own
* backend instance — reference equality on `raw` would fail across tabs).
*
* @example
* ```ts
* import { createBroadcastCrossTab } from "@stainless-code/persist/transport/crosstab";
* import { createIdbStorage } from "@stainless-code/persist/backends/idb";
* import { persistStore } from "@stainless-code/persist/sources/tanstack-store";
*
* const bridge = createBroadcastCrossTab({ channelName: "app:prefs" })!;
* const persist = persistStore(store, {
*   name: "app:prefs:v1",
*   storage: bridge.wrap(createIdbStorage()!),
*   crossTab: true,
*   crossTabEventTarget: bridge.crossTabEventTarget,
* });
* // on teardown: persist.destroy(); bridge.close();
* ```
*/
function createBroadcastCrossTab(options) {
	if (typeof BroadcastChannel === "undefined") return;
	const channel = new BroadcastChannel(options.channelName);
	const handlerMap = /* @__PURE__ */ new Map();
	const crossTabEventTarget = {
		addEventListener(_type, listener) {
			const handler = (event) => {
				listener(event.data);
			};
			handlerMap.set(listener, handler);
			channel.addEventListener("message", handler);
		},
		removeEventListener(_type, listener) {
			const handler = handlerMap.get(listener);
			if (handler) {
				channel.removeEventListener("message", handler);
				handlerMap.delete(listener);
			}
		}
	};
	function postMessage(message) {
		try {
			channel.postMessage(message);
		} catch {}
	}
	return {
		crossTabEventTarget,
		wrap(storage) {
			return {
				getItem: (name) => storage.getItem(name),
				raw: storage.raw,
				setItem(name, value) {
					const result = storage.setItem(name, value);
					Promise.resolve(result).then(() => {
						postMessage({
							key: name,
							newValue: "1",
							storageArea: null
						});
					}).catch(() => {});
					return result;
				},
				removeItem(name) {
					const present = Promise.resolve(storage.getItem(name)).then((v) => v != null, () => true);
					const result = storage.removeItem(name);
					present.then((wasPresent) => {
						if (!wasPresent) return;
						Promise.resolve(result).then(() => {
							postMessage({
								key: name,
								newValue: null,
								storageArea: null
							});
						}).catch(() => {});
					});
					return result;
				}
			};
		},
		close() {
			for (const handler of handlerMap.values()) channel.removeEventListener("message", handler);
			handlerMap.clear();
			channel.close();
		}
	};
}
//#endregion
export { createBroadcastCrossTab };