`useSliceIdsListener`

The useSliceIdsListener hook registers a listener function with the Indexes object that will be called whenever the Slice Ids in an Index change.

useSliceIdsListener(
  indexId: IdOrNull,
  listener: SliceIdsListener,
  listenerDeps?: DependencyList,
  indexesOrIndexesId?: IndexesOrIndexesId,
): void

	Type	Description
`indexId`	`IdOrNull`	The `Id` of the `Index` to listen to, or `null` as a wildcard.
`listener`	`SliceIdsListener`	The function that will be called whenever the `Slice` `Ids` in the `Index` change.
`listenerDeps?`	`DependencyList`	An optional array of dependencies for the `listener` function, which, if any change, result in the re-registration of the listener. This parameter defaults to an empty array.
`indexesOrIndexesId?`	`IndexesOrIndexesId`	The `Indexes` object to register the listener with: omit for the default context `Indexes` object, provide an `Id` for a named context `Indexes` object, or provide an explicit reference.
returns	`void`	This has no return value.

This hook is useful for situations where a component needs to register its own specific listener to do more than simply tracking the value (which is more easily done with the useSliceIds hook).

You can either listen to a single Index (by specifying the Index Id as the method's first parameter), or changes to any Index (by providing a null wildcard).

Unlike the addSliceIdsListener method, which returns a listener Id and requires you to remove it manually, the useSliceIdsListener hook manages this lifecycle for you: when the listener changes (per its listenerDeps dependencies) or the component unmounts, the listener on the underlying Indexes object will be deleted.

Example

This example uses the useSliceIdsListener hook to create a listener that is scoped to a single component. When the component is unmounted, the listener is removed from the Indexes object.

import {Provider, useSliceIdsListener} from 'tinybase/ui-react';
import {createIndexes, createStore} from 'tinybase';
import React from 'react';
import {createRoot} from 'react-dom/client';

const App = ({indexes}) => (
  <Provider indexes={indexes}>
    <Pane />
  </Provider>
);
const Pane = () => {
  useSliceIdsListener('bySpecies', () => console.log('Slice Ids changed'));
  return <span>App</span>;
};

const store = createStore().setTable('pets', {
  fido: {species: 'dog'},
  felix: {species: 'cat'},
  cujo: {species: 'dog'},
});
const indexes = createIndexes(store);
indexes.setIndexDefinition('bySpecies', 'pets', 'species');

const app = document.createElement('div');
const root = createRoot(app);
root.render(<App indexes={indexes} />);
console.log(indexes.getListenerStats().sliceIds);
// -> 1

store.setRow('pets', 'lowly', {species: 'worm'});
// -> 'Slice Ids changed'

root.unmount();
console.log(indexes.getListenerStats().sliceIds);
// -> 0

Since

v1.0.0