reactiveIndex()

Creates a reactive secondary index from index key to sets of primary keys.

Signature

function reactiveIndex(opts?: ReactiveIndexCreateOptions): ReactiveIndex

Parameters

Parameter	Type	Description
opts	ReactiveIndexCreateOptions	Optional configuration.

Returns

ReactiveIndex — reverse mapping queries, reactive selectors, mutation helpers, and snapshot APIs.

Basic Usage

import { reactiveIndex } from "callbag-recharge/data";

const byTag = reactiveIndex();
byTag.add("u1", ["admin", "active"]);
byTag.get("admin"); // Set { "u1" }

Options / Behavior Details

• Reverse map: Tracks primary key to index keys for efficient remove() and update().
• Reactive selectors: select(indexKey) returns cached stores for index-key membership updates.
• Structural versioning: keysStore/sizeStore are version-gated and update on keyset changes.

Examples

Update indexed keys

const byTag = reactiveIndex();
byTag.add("u1", ["admin"]);
byTag.update("u1", ["editor"]);

byTag.get("admin").size; // 0
byTag.get("editor").size; // 1

See Also

• reactiveMap
• reactiveList
• pubsub