API reference › @evolu/common › local‑first/Evolu › subscribeAppOwnerState

function subscribeAppOwnerState<
  S extends Readonly<
    Record<string, Readonly<Record<string, AnyStandardSchemaV1>>>
  >,
>(
  current: ReadonlyStore<CurrentAppOwner<S> | null>,
  onChange: (state: AppOwnerState<S>) => void,
): Unsubscribe;

Defined in: packages/common/src/local-first/Evolu.ts:2220

Follows current, such as EvoluApp.current, as an AppOwnerState, and calls onChange with the state at once and whenever it changes. Another instance, as when the tab opens another AppOwner, or the AppOwner again after a removal and restore or its database's deletion, is Opening until its promise resolves, and then Open, so a UI keyed by the instance remounts. Another CurrentAppOwner with the same instance keeps the state's type and instance, with the new current. An instance that opens after the tab moved on changes nothing, and one that never opens, as an aborted open's, leaves the state Opening. Once unsubscribed, an instance that opens changes nothing.

The UI bindings follow the app with it, and so can an app without one.

Example

import {
  assertType,
  subscribeAppOwnerState,
  type EvoluApp,
  type Name,
  type TestEvoluSchema,
  type Unsubscribe,
} from "@evolu/common";

// Renders the open AppOwner's database name, or what shows meanwhile.
const renderApp = (
  app: EvoluApp<TestEvoluSchema>,
  render: (text: Name | "Opening" | "None") => void,
): Unsubscribe =>
  subscribeAppOwnerState(app.current, (state) => {
    render(state.type === "Open" ? state.evolu.name : state.type);
  });

assertType<ReturnType<typeof renderApp>, Unsubscribe>();
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