StorageTransport

Cross-tab delivery over the storage event, for browsers with no BroadcastChannel.

The mechanism is a quirk turned to advantage: writing to localStorage fires a storage event in every other same-origin tab and never in the writer — exactly BroadcastChannel’s no-self-echo semantics, for free.

Two differences from the real thing, both deliberate and both documented:

1. Fidelity is JSON, not structured clone. localStorage holds strings. The default serializer therefore rejects every value JSON would quietly change — a Date, a Map, a function — rather than let a write appear to succeed while peers receive something else. Pass a Serializer (devalue, superjson) to carry those instead.
2. The entry is removed immediately after writing. Peers have already been notified by then (the event carries the value), and leaving application state sitting in localStorage would be both a quota cost and a privacy one. The removal fires a second event with a null newValue, which receivers ignore.

Implements

• Transport

Constructors

Constructor

new StorageTransport(
   name,
   storage?,
   serializer?): StorageTransport;

Parameters

Parameter	Type	Default value
name	string	undefined
storage	Storage	globalThis.localStorage
serializer	Serializer	jsonSerializer

Returns

StorageTransport

Properties

kind

readonly kind: TransportKind = 'storage';

What this transport is. Optional so a custom transport need not declare one.

Implementation of

Transport.kind

Methods

close()

close(): void;

Returns

void

Implementation of

Transport.close

---

post()

post(data): void;

Parameters

Parameter	Type
data	unknown

Returns

void

Implementation of

Transport.post

---

subscribe()

subscribe(listener): () => void;

Parameters

Parameter	Type
listener	(data) => void

Returns

() => void

Implementation of

Transport.subscribe