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The useHasValueListener hook registers a listener function with the Store that will be called when a Value is added to or removed from the Store.

  valueId: IdOrNull,
  listener: HasValueListener,
  listenerDeps?: DependencyList,
  mutator?: boolean,
  storeOrStoreId?: StoreOrStoreId,
): void

The Id of the Value to listen to, or null as a wildcard.


The function that will be called whenever the matching Value is added or removed.


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.


An optional boolean that indicates that the listener mutates Store data.


The Store to register the listener with: omit for the default context Store, provide an Id for a named context Store, or provide an explicit reference.


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 useHasValue hook).

You can either listen to a single Value being added or removed (by specifying the Value Id) or any Value being added or removed (by providing a null wildcard).

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


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

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

const App = ({store}) => (
  <Provider store={store}>
    <Pane />
const Pane = () => {
  useHasValueListener('open', () =>
    console.log('Value existence changed'),
  return <span>App</span>;

const store = createStore();
const app = document.createElement('div');
const root = createRoot(app);
root.render(<App store={store} />);
// -> 1

store.setValue('open', false);
// -> 'Value existence changed'

// -> 0