Events

Storage emits four event types and exposes subscription helpers for React useSyncExternalStore.

Event types

Event	When it fires	Callback args
`set`	After a successful `set`	`(key, value)`
`del`	After `del` or expiry removal	`(key, undefined)`
`expired`	Key passed expiry (before optional delete)	`(key, value)`
`flush`	After `flushAll`	`("", undefined)`

`on` / `off`

const cache = createStorage();

cache.on("set", (key, value) => {
  console.log("set", key, value);
});

cache.on("expired", (key, value) => {
  console.log("expired", key, value);
});

const handler = (key: string) => console.log("deleted", key);
cache.on("del", handler);
cache.off("del", handler);

Event listeners are in-process only. Cross-tab invalidation uses the cache bus, not these callbacks.

React subscriptions

subscribe and subscribeAll notify useSyncExternalStore without exposing values in the callback (read via getSnapshot instead).

const cache = createStorage();

// Per-key
const unsub = cache.subscribe("ui:theme", () => {
  console.log("theme changed", cache.get("ui:theme"));
});

// Global
cache.subscribeAll(() => console.log("any change"));

@brushy/storage-react wires these internally; you rarely call them directly unless building custom hooks.

Remote invalidation events

When a cache bus delivers remote events, the instance:

del / expired: removes the key from memory and persist, notifies subscribers
flush: clears all keys
set: drops the in-memory copy (invalidates without replicating the remote value)

This keeps tabs and runtimes consistent without broadcasting full payloads by default.

Overview

Features

@brushy/storage-react

Migration

Event types

`on` / `off`

React subscriptions

Remote invalidation events

​Event types

​on / off

​React subscriptions

​Remote invalidation events

Event types

`on` / `off`

React subscriptions

Remote invalidation events