Message Lifecycle

Expiration

Send a message with an expiry when it only matters for a while:

postMessage('invite', { to: 'tab-2' }, { expirationDuration: 5 * 60 * 1000 }); // 5 minutes
// or an absolute moment:
postMessage('invite', { to: 'tab-2' }, { expirationDate: Date.now() + 60_000 });

Expired messages are removed from state on a cleanup pass. Two options control the cadence:

• cleaningInterval (default 1000 ms) - how often cleanup runs.
• cleanupDebounceMs (default 0) - debounce applied to cleanup, useful under rapid updates.

Keep cleanupDebounceMs smaller than cleaningInterval. If the debounce is longer, every interval tick restarts it and expired messages may never be removed.

Deduplication

A received message is dropped if its message ID was seen within deduplicationTTL (default 5 minutes). Deduplication is by ID, not content: sending the same payload twice produces two distinct messages, and it does not protect you from rebroadcast loops (see Sync shared state).

Tune deduplicationTTL to your message frequency: lower it for high-volume channels where IDs should be forgotten sooner, raise it when redelivery within minutes is likely and must be ignored.

keepLatestMessage

With keepLatestMessage: true, messages holds only the single most recent message across all types. Good for “current status” channels; the wrong tool when you need the latest per type (use registeredTypes or separate channels instead).

Clearing

Remove messages selectively or in bulk:

// Received log
clearReceivedMessages(); // everything
clearReceivedMessages({ types: ['alert'] }); // by type
clearReceivedMessages({ sources: ['tab-2'] }); // by source
clearReceivedMessages({ ids: [id] }); // by message id

// Sent log
clearSentMessages();
clearSentMessages({ sync: true }); // also tells other tabs to clear their received copies

clearSentMessages({ sync: true }) broadcasts an internal clear message so the other tabs drop their received copies of what you sent. Internal clear messages never appear in messages and never trigger onMessage.