npm package: @genie-design/tinybase
Description: The reactive data store for local-first apps.
Author: jamesgpearce
Latest version: 5.1.6

<section id="hero"><h2 id="the-reactive-data-store-for-local-first-apps">The <em>reactive</em> data store for <span>local-first apps</span>.</h2></section><p><a href="https://tinybase.org/guides/releases/#v5-1"><em>NEW!</em> v5.1 release</a></p><p><span id="one-with">&quot;The One You Can Sync... with a server!&quot;</span></p><p><a class="start" href="https://tinybase.org/guides/the-basics/getting-started/">Get started</a></p><p><a href="https://tinybase.org/demos/">Try the demos</a></p><p><a href="https://tinybase.org/api/store/interfaces/store/store/">Read the docs</a></p><hr><section><h2 id="it-s-reactive">It&#x27;s <em>Reactive</em></h2><p>TinyBase lets you <a href="#register-granular-listeners">listen to changes</a> made to any part of your data. This means your app will be fast, since you only spend rendering cycles on things that change. The optional <a href="#call-hooks-to-bind-to-data">bindings to React</a> and <a href="#pre-built-reactive-components">pre-built components</a> let you easily build fully reactive UIs on top of TinyBase. You even get a built-in <a href="#set-checkpoints-for-an-undo-stack">undo stack</a>, and <a href="#an-inspector-for-your-data">developer tools</a>!</p></section><section><h2 id="it-s-database-like">It&#x27;s <em>Database-Like</em></h2><p>Consumer app? Enterprise app? Or even a game? Model <a href="#start-with-a-simple-key-value-store">key-value data</a> and <a href="#level-up-to-use-tabular-data">tabular data</a> with optional typed <a href="#apply-schemas-to-tables-values">schematization</a>, whatever its data structures. There are built-in <a href="#create-indexes-for-fast-lookups">indexing</a>, <a href="#define-metrics-and-aggregations">metric aggregation</a>, and tabular <a href="#model-table-relationships">relationships</a> APIs - and a powerful <a href="#build-complex-queries-with-tinyql">query engine</a> to select, join, filter, and group data (reactively!) without SQL.</p></section><section><h2 id="it-synchronizes">It <em>Synchronizes</em></h2><p>TinyBase has <a href="#synchronize-between-devices">native CRDT</a> support, meaning that you can deterministically <a href="https://tinybase.org/guides/synchronization/">synchronize</a> and merge data across multiple sources, clients, and servers. And although TinyBase is an in-memory data store, but you can easily <a href="#persist-to-storage-sqlite-more">persist</a> your data to file, <a href="https://tinybase.org/api/persister-browser">browser storage</a>, <a href="https://tinybase.org/api/persister-indexed-db">IndexedDB</a>, <a href="https://tinybase.org/guides/persistence/database-persistence/">SQLite databases</a>, and <a href="https://tinybase.org/guides/persistence/third-party-crdt-persistence/">more</a>.</p></section><section><h2 id="it-s-built-for-a-local-first-world">It&#x27;s Built For A <em>Local-First</em> World</h2><p>TinyBase works anywhere that JavaScript does, but it&#x27;s especially great for local-first apps: where data is stored locally on the user&#x27;s device and that can be run offline. It&#x27;s tiny by name, tiny by nature: just <a href="#did-we-say-tiny">5.3kB - 12.7kB</a> and with no dependencies - yet <a href="#well-tested-and-documented">100% tested</a>, <a href="https://tinybase.org/guides/the-basics/getting-started/">fully documented</a>, and of course, <a href="https://github.com/tinyplex/tinybase">open source</a>!</p></section><hr><section id="friends"><h2 id="tinybase-works-great-on-its-own-but-also-plays-well-with-friends">TinyBase works great on its own, but also plays well with friends!</h2><div><a href="https://tinybase.org/guides/building-uis/getting-started-with-ui-react"><img width="48" src="https://tinybase.org/react.svg"> React</a></div><div><a href="https://tinybase.org/api/persister-partykit-client"><img width="48" src="https://tinybase.org/partykit.svg"> PartyKit</a></div><div><a href="https://tinybase.org/guides/schemas-and-persistence/database-persistence"><img width="48" src="https://tinybase.org/expo.svg">Expo SQLite</a></div><div><a href="https://tinybase.org/guides/schemas-and-persistence/database-persistence"><img width="48" src="https://tinybase.org/electric.svg">ElectricSQL</a></div><div><a href="https://tinybase.org/guides/schemas-and-persistence/database-persistence"><img width="48" src="https://tinybase.org/sqlite.svg"> SQLite</a></div><div><a href="https://tinybase.org/guides/schemas-and-persistence/database-persistence"><img width="48" src="https://tinybase.org/turso.svg">Turso</a></div><div><a href="https://tinybase.org/guides/schemas-and-persistence/database-persistence"><img width="48" src="https://tinybase.org/powersync.svg">PowerSync</a></div><div><a href="https://tinybase.org/api/persister-indexed-db/functions/creation/createindexeddbpersister"><img width="48" src="https://tinybase.org/indexeddb.svg"> IndexedDB</a></div><div><a href="https://tinybase.org/api/persister-yjs/functions/creation/createyjspersister"><img width="48" src="https://tinybase.org/yjs.svg"> YJS</a></div><div><a href="https://tinybase.org/api/persister-cr-sqlite-wasm"><img width="48" src="https://tinybase.org/crsqlite.png"> CR-SQLite</a></div><div><a href="https://tinybase.org/api/persister-automerge"><img width="48" src="https://tinybase.org/automerge.svg"> Automerge</a></div></section><hr><section id="follow"><a href="https://github.com/tinyplex/tinybase" target="_blank"><img src="https://img.shields.io/github/stars/tinyplex/tinybase?style=for-the-badge&amp;logo=GitHub&amp;logoColor=%23fff&amp;label=GitHub&amp;labelColor=%23d81b60&amp;color=%23333"> </a><a href="https://discord.com/invite/mGz3mevwP8" target="_blank"><img src="https://img.shields.io/discord/1027918215323590676?style=for-the-badge&amp;logo=discord&amp;logoColor=%23fff&amp;label=Discord&amp;labelColor=%233131e8&amp;color=%23333"> </a><a href="https://twitter.com/tinybasejs" target="_blank"><img src="https://img.shields.io/twitter/follow/tinybasejs?style=for-the-badge&amp;logo=x&amp;logoColor=%23fff&amp;label=Twitter&amp;labelColor=%23333&amp;color=%23333"></a><br><a href="https://github.com/tinyplex/tinybase/discussions" target="_blank"><img src="https://img.shields.io/github/discussions/tinyplex/tinybase?style=for-the-badge&amp;logo=GitHub&amp;logoColor=%23fff&amp;label=Ideas&amp;labelColor=%23d81b60&amp;color=%23333"> </a><a href="https://github.com/tinyplex/tinybase/issues" target="_blank"><img src="https://img.shields.io/github/issues/tinyplex/tinybase?style=for-the-badge&amp;logo=GitHub&amp;logoColor=%23fff&amp;label=Issues&amp;labelColor=%23d81b60&amp;color=%23333"> </a><a href="#well-tested-and-documented"><img src="https://img.shields.io/badge/Tests-100%25-green?style=for-the-badge&amp;logo=jest&amp;logoColor=%23fff&amp;color=%23333&amp;labelColor=%2387c305"> </a><a href="https://www.npmjs.com/package/tinybase/v/5.1.5" target="_blank"><img src="https://img.shields.io/npm/v/tinybase?style=for-the-badge&amp;logo=npm&amp;logoColor=%23fff&amp;labelColor=%23bd0005&amp;color=%23333"></a></section><hr><section><h2 id="start-with-a-simple-key-value-store">Start with a simple key-value store.</h2><p>Creating a <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a> requires just a simple call to the <a href="https://tinybase.org/api/store/functions/creation/createstore/"><code>createStore</code></a> function. Once you have one, you can easily set <a href="https://tinybase.org/api/store/type-aliases/store/values/"><code>Values</code></a> in it by unique <a href="https://tinybase.org/api/common/type-aliases/identity/id/"><code>Id</code></a>. And of course you can easily get them back out again.</p><p>Read more about using keyed value data in <a href="https://tinybase.org/guides/the-basics/">The Basics</a> guide.</p></section>

```js
import {createStore} from 'tinybase';

const store = createStore()
  .setValues({employees: 3})
  .setValue('open', true);

console.log(store.getValues());
// -> {employees: 3, open: true}
```

<section><h2 id="level-up-to-use-tabular-data">Level up to use tabular data.</h2><p>For other types of data applications, a tabular data structure is more useful. TinyBase lets you set and get nested <a href="https://tinybase.org/api/store/type-aliases/store/table/"><code>Table</code></a>, <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a>, or <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a> data, by unique <a href="https://tinybase.org/api/common/type-aliases/identity/id/"><code>Id</code></a> - and in the same <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a> as the keyed values!</p><p>Read more about setting and changing data in <a href="https://tinybase.org/guides/the-basics/">The Basics</a> guide.</p></section>

```js
store
  .setTable('pets', {fido: {species: 'dog'}})
  .setCell('pets', 'fido', 'color', 'brown');

console.log(store.getRow('pets', 'fido'));
// -> {species: 'dog', color: 'brown'}
```

<section><h2 id="register-granular-listeners">Register granular listeners.</h2><p>The magic starts to happen when you register listeners on a <a href="https://tinybase.org/api/store/type-aliases/store/value/"><code>Value</code></a>, <a href="https://tinybase.org/api/store/type-aliases/store/table/"><code>Table</code></a>, <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a>, or <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a>. They get called when any part of that object changes. You can also use wildcards - useful when you don&#x27;t know the <a href="https://tinybase.org/api/common/type-aliases/identity/id/"><code>Id</code></a> of the objects that might change.</p><p>Read more about listeners in the <a href="https://tinybase.org/guides/the-basics/listening-to-stores/">Listening To Stores</a> guide.</p></section>

```js
const listenerId = store.addTableListener('pets', () =>
  console.log('changed'),
);

store.setCell('pets', 'fido', 'sold', false);
// -> 'changed'

store.delListener(listenerId);
```

<section><h2 id="call-hooks-to-bind-to-data">Call hooks to bind to data.</h2><p>If you&#x27;re using React in your application, the optional <a href="https://tinybase.org/api/ui-react/"><code>ui-react</code></a> module provides hooks to bind to the data in a <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a>.</p><p>More magic! The <a href="https://tinybase.org/api/ui-react/functions/store-hooks/usecell/"><code>useCell</code></a> hook in this example fetches the dog&#x27;s color. But it also registers a listener on that cell that will fire and re-render the component whenever the value changes.</p><p>Basically you simply describe what data you want in your user interface and TinyBase will take care of the whole lifecycle of updating it for you.</p><p>Read more about the using hooks in the <a href="https://tinybase.org/guides/building-uis/using-react-hooks/">Using React Hooks</a> guide.</p></section>

```jsx
import React from 'react';
import {createRoot} from 'react-dom/client';
import {useCell} from 'tinybase/ui-react';

const App1 = () => {
  const color = useCell('pets', 'fido', 'color', store);
  return <>Color: {color}</>;
};

const app = document.createElement('div');
const root = createRoot(app);
root.render(<App1 />);
console.log(app.innerHTML);
// -> 'Color: brown'

store.setCell('pets', 'fido', 'color', 'walnut');
console.log(app.innerHTML);
// -> 'Color: walnut'
```

<section><h2 id="pre-built-reactive-components">Pre-built reactive components.</h2><p>The <a href="https://tinybase.org/api/ui-react/"><code>ui-react</code></a> module provides bare React components that let you build up a fully reactive user interface based on a <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a>.</p><p>For web applications in particular, the new <a href="https://tinybase.org/api/ui-react-dom/"><code>ui-react-dom</code></a> module provides pre-built components for tabular display of your data, with lots of customization and interactivity options.</p><p>Try them out in the <a href="https://tinybase.org/demos/ui-components/">UI Components</a> demos, and read more about the underlying <a href="https://tinybase.org/api/ui-react/"><code>ui-react</code></a> module in the <a href="https://tinybase.org/guides/building-uis/">Building UIs</a> guides.</p></section><img src="https://tinybase.org/ui-react-dom.webp"><section><h2 id="an-inspector-for-your-data">An inspector for your data.</h2><p>If you are building a web application, the new <a href="https://tinybase.org/api/ui-react-inspector/functions/development-components/inspector/"><code>Inspector</code></a> component lets you overlay a view of the data in your <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a>, <a href="https://tinybase.org/api/indexes/interfaces/indexes/indexes/"><code>Indexes</code></a>, <a href="https://tinybase.org/api/relationships/interfaces/relationships/relationships/"><code>Relationships</code></a>, and so on. You can even edit the data in place and see it update in your app immediately.</p><p>Read more about this powerful new tool in the <a href="https://tinybase.org/guides/developer-tools/inspecting-data/">Inspecting Data</a> guide.</p></section><img src="https://tinybase.org/store-inspector.webp"><section><h2 id="apply-schemas-to-tables-values">Apply schemas to tables &amp; values.</h2><p>By default, a <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a> can contain any arbitrary <a href="https://tinybase.org/api/store/type-aliases/store/value/"><code>Value</code></a>, and a <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a> can contain any arbitrary <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a>. But you can add a <a href="https://tinybase.org/api/store/type-aliases/schema/valuesschema/"><code>ValuesSchema</code></a> or a <a href="https://tinybase.org/api/store/type-aliases/schema/tablesschema/"><code>TablesSchema</code></a> to a <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a> to ensure that the values are always what you expect: constraining their types, and providing defaults.</p><p>In this example, we set a new <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a> without the <code>sold</code> <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a> in it. The schema ensures it&#x27;s present with default of <code>false</code>.</p><p>Read more about schemas in the <a href="https://tinybase.org/guides/schemas/">Schemas</a> guide.</p></section>

```js
store.setTablesSchema({
  pets: {
    species: {type: 'string'},
    color: {type: 'string'},
    sold: {type: 'boolean', default: false},
  },
});

store.setRow('pets', 'polly', {species: 'parrot'});
console.log(store.getRow('pets', 'polly'));
// -> {species: 'parrot', sold: false}

store.delTablesSchema();
```

<section><h2 id="synchronize-between-devices">Synchronize between devices.</h2><p>The <a href="https://tinybase.org/api/mergeable-store/interfaces/mergeable/mergeablestore/"><code>MergeableStore</code></a> type acts as a native CRDT, letting you merge data and synchronize it between clients and systems - or even a server. The synchronization protocol can run over WebSockets, the browser BroadcastChannel, or your own custom synchronization medium.</p><p>Read more about these techniques in the <a href="https://tinybase.org/guides/synchronization/">Synchronization</a> guides.</p></section>

```js
import {WebSocketServer, WebSocket} from 'ws';
import {createMergeableStore} from 'tinybase';
import {createWsServer} from 'tinybase/synchronizers/synchronizer-ws-server';
import {createWsSynchronizer} from 'tinybase/synchronizers/synchronizer-ws-client';

// On a server machine:
const server = createWsServer(
  new WebSocketServer({port: 8040}),
);

// On a client machine:
const store1 = createMergeableStore();
const synchronizer1 = await createWsSynchronizer(
  store1,
  new WebSocket('ws://localhost:8040'),
);
await synchronizer1.startSync();

// ...

synchronizer1.destroy();
server.destroy();
```

<section><h2 id="persist-to-storage-sqlite-more">Persist to storage, SQLite, &amp; more.</h2><p>You can easily persist a <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a> between browser page reloads or sessions. You can also synchronize it with a web endpoint, or (if you&#x27;re using TinyBase in an appropriate environment), load and save it to a file. You can bind TinyBase to various flavors of <a href="https://tinybase.org/guides/schemas-and-persistence/database-persistence/">SQLite</a>, or to <a href="https://yjs.dev/">Yjs</a> and <a href="https://automerge.org/">Automerge</a> CRDT documents.</p><p>Read more about persisters in the <a href="https://tinybase.org/guides/persistence/">Persistence</a> guides.</p></section>

```js
import {createSessionPersister} from 'tinybase/persisters/persister-browser';

const persister = createSessionPersister(store, 'demo');
await persister.save();

console.log(sessionStorage.getItem('demo'));
// ->
`
[
  {
    "pets":{
      "fido":{"species":"dog","color":"walnut","sold":false},
      "polly":{"species":"parrot","sold":false}
    }
  },
  {"employees":3,"open":true}
]
`;

persister.destroy();
sessionStorage.clear();
```

<section><h2 id="build-complex-queries-with-tinyql">Build complex queries with <a href="https://tinybase.org/guides/using-queries/tinyql/">TinyQL</a>.</h2><p>The <a href="https://tinybase.org/api/queries/interfaces/queries/queries/"><code>Queries</code></a> object lets you query data across tables, with filtering and aggregation - using a SQL-adjacent syntax called <a href="https://tinybase.org/guides/using-queries/tinyql/">TinyQL</a>.</p><p>Accessors and listeners let you sort and paginate the results efficiently, making building rich tabular interfaces easier than ever.</p><p>In this example, we have two tables: of pets and their owners. They are joined together by the pet&#x27;s ownerId <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a>. We select the pet&#x27;s species, and the owner&#x27;s state, and then aggregate the prices for the combinations.</p><p>We access the results by descending price, essentially answering the question: &quot;which is the highest-priced species, and in which state?&quot;</p><p>Needless to say, the results are reactive too! You can add listeners to queries just as easily as you do to raw tables.</p><p>Read more about <a href="https://tinybase.org/api/queries/interfaces/queries/queries/"><code>Queries</code></a> in the <a href="https://tinybase.org/guides/releases/#v2-0">v2.0 Release Notes</a>, the <a href="https://tinybase.org/guides/using-queries/">Using Queries</a> guide, and the <a href="https://tinybase.org/demos/car-analysis/">Car Analysis</a> demo and <a href="https://tinybase.org/demos/movie-database/">Movie Database</a> demo.</p></section>

```js
import {createQueries} from 'tinybase';

store
  .setTable('pets', {
    fido: {species: 'dog', ownerId: '1', price: 5},
    rex: {species: 'dog', ownerId: '2', price: 4},
    felix: {species: 'cat', ownerId: '2', price: 3},
    cujo: {species: 'dog', ownerId: '3', price: 4},
  })
  .setTable('owners', {
    1: {name: 'Alice', state: 'CA'},
    2: {name: 'Bob', state: 'CA'},
    3: {name: 'Carol', state: 'WA'},
  });

const queries = createQueries(store);
queries.setQueryDefinition(
  'prices',
  'pets',
  ({select, join, group}) => {
    select('species');
    select('owners', 'state');
    select('price');
    join('owners', 'ownerId');
    group('price', 'avg').as('avgPrice');
  },
);

queries
  .getResultSortedRowIds('prices', 'avgPrice', true)
  .forEach((rowId) => {
    console.log(queries.getResultRow('prices', rowId));
  });
// -> {species: 'dog', state: 'CA', avgPrice: 4.5}
// -> {species: 'dog', state: 'WA', avgPrice: 4}
// -> {species: 'cat', state: 'CA', avgPrice: 3}

queries.destroy();
```

<section><h2 id="define-metrics-and-aggregations">Define metrics and aggregations.</h2><p>A <a href="https://tinybase.org/api/metrics/interfaces/metrics/metrics/"><code>Metrics</code></a> object makes it easy to keep a running aggregation of <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a> values in each <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a> of a <a href="https://tinybase.org/api/store/type-aliases/store/table/"><code>Table</code></a>. This is useful for counting rows, but also supports averages, ranges of values, or arbitrary aggregations.</p><p>In this example, we create a new table of the pet species, and keep a track of which is most expensive. When we add horses to our pet store, the listener detects that the highest price has changed.</p><p>Read more about <a href="https://tinybase.org/api/metrics/interfaces/metrics/metrics/"><code>Metrics</code></a> in the <a href="https://tinybase.org/guides/using-metrics/">Using Metrics</a> guide.</p></section>

```js
import {createMetrics} from 'tinybase';

store.setTable('species', {
  dog: {price: 5},
  cat: {price: 4},
  worm: {price: 1},
});

const metrics = createMetrics(store);
metrics.setMetricDefinition(
  'highestPrice', // metricId
  'species', //      tableId to aggregate
  'max', //          aggregation
  'price', //        cellId to aggregate
);

console.log(metrics.getMetric('highestPrice'));
// -> 5

metrics.addMetricListener('highestPrice', () =>
  console.log(metrics.getMetric('highestPrice')),
);
store.setCell('species', 'horse', 'price', 20);
// -> 20

metrics.destroy();
```

<section><h2 id="create-indexes-for-fast-lookups">Create indexes for fast lookups.</h2><p>An <a href="https://tinybase.org/api/indexes/interfaces/indexes/indexes/"><code>Indexes</code></a> object makes it easy to look up all the <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a> objects that have a certain value in a <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a>.</p><p>In this example, we create an index on the <code>species</code> <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a> values. We can then get the the list of distinct <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a> value present for that index (known as &#x27;slices&#x27;), and the set of <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a> objects that match each value.</p><p><a href="https://tinybase.org/api/indexes/interfaces/indexes/indexes/"><code>Indexes</code></a> objects are reactive too. So you can set listeners on them just as you do for the data in the underlying <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a>.</p><p>Read more about <a href="https://tinybase.org/api/indexes/interfaces/indexes/indexes/"><code>Indexes</code></a> in the <a href="https://tinybase.org/guides/using-indexes/">Using Indexes</a> guide.</p></section>

```js
import {createIndexes} from 'tinybase';

const indexes = createIndexes(store);
indexes.setIndexDefinition(
  'bySpecies', // indexId
  'pets', //      tableId to index
  'species', //   cellId to index
);

console.log(indexes.getSliceIds('bySpecies'));
// -> ['dog', 'cat']
console.log(indexes.getSliceRowIds('bySpecies', 'dog'));
// -> ['fido', 'rex', 'cujo']

indexes.addSliceIdsListener('bySpecies', () =>
  console.log(indexes.getSliceIds('bySpecies')),
);
store.setRow('pets', 'lowly', {species: 'worm'});
// -> ['dog', 'cat', 'worm']

indexes.destroy();
```

<section><h2 id="model-table-relationships">Model table relationships.</h2><p>A <a href="https://tinybase.org/api/relationships/interfaces/relationships/relationships/"><code>Relationships</code></a> object lets you associate a <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a> in a local <a href="https://tinybase.org/api/store/type-aliases/store/table/"><code>Table</code></a> with the <a href="https://tinybase.org/api/common/type-aliases/identity/id/"><code>Id</code></a> of a <a href="https://tinybase.org/api/store/type-aliases/store/row/"><code>Row</code></a> in a remote <a href="https://tinybase.org/api/store/type-aliases/store/table/"><code>Table</code></a>. You can also reference a table to itself to create linked lists.</p><p>In this example, the <code>species</code> <a href="https://tinybase.org/api/store/type-aliases/store/cell/"><code>Cell</code></a> of the <code>pets</code> <a href="https://tinybase.org/api/store/type-aliases/store/table/"><code>Table</code></a> is used to create a relationship to the <code>species</code> <a href="https://tinybase.org/api/store/type-aliases/store/table/"><code>Table</code></a>, so that we can access the price of a given pet.</p><p>Like everything else, you can set listeners on <a href="https://tinybase.org/api/relationships/interfaces/relationships/relationships/"><code>Relationships</code></a> too.</p><p>Read more about <a href="https://tinybase.org/api/relationships/interfaces/relationships/relationships/"><code>Relationships</code></a> in the <a href="https://tinybase.org/guides/using-relationships/">Using Relationships</a> guide.</p></section>

```js
import {createRelationships} from 'tinybase';

const relationships = createRelationships(store);
relationships.setRelationshipDefinition(
  'petSpecies', // relationshipId
  'pets', //       local tableId to link from
  'species', //    remote tableId to link to
  'species', //    cellId containing remote key
);

console.log(
  store.getCell(
    relationships.getRemoteTableId('petSpecies'),
    relationships.getRemoteRowId('petSpecies', 'fido'),
    'price',
  ),
);
// -> 5

relationships.destroy();
```

<section><h2 id="set-checkpoints-for-an-undo-stack">Set checkpoints for an undo stack.</h2><p>A <a href="https://tinybase.org/api/checkpoints/interfaces/checkpoints/checkpoints/"><code>Checkpoints</code></a> object lets you set checkpoints on a <a href="https://tinybase.org/api/store/interfaces/store/store/"><code>Store</code></a>. Move forward and backward through them to create undo and redo functions.</p><p>In this example, we set a checkpoint, then sell one of the pets. Later, the pet is brought back to the shop, and we go back to that checkpoint to revert the store to its previous state.</p><p>Read more about <a href="https://tinybase.org/api/checkpoints/interfaces/checkpoints/checkpoints/"><code>Checkpoints</code></a> in the <a href="https://tinybase.org/guides/using-checkpoints/">Using Checkpoints</a> guide.</p></section>

```js
import {createCheckpoints} from 'tinybase';

const checkpoints = createCheckpoints(store);

store.setCell('pets', 'felix', 'sold', false);
checkpoints.addCheckpoint('pre-sale');

store.setCell('pets', 'felix', 'sold', true);
console.log(store.getCell('pets', 'felix', 'sold'));
// -> true

checkpoints.goBackward();
console.log(store.getCell('pets', 'felix', 'sold'));
// -> false
```

<section><h2 id="type-definitions-orm-like-apis">Type definitions &amp; ORM-like APIs</h2><p>TinyBase has comprehensive type definitions, and even offers definitions that infer API types from the data schemas you apply.</p><p>Furthermore, you can easily create TypeScript <code>.d.ts</code> definitions that model your data and encourage type-safety when reading and writing data - as well as <code>.ts</code> implementations that provide ORM-like methods for your named tables.</p><p>Read more about type support in the <a href="https://tinybase.org/guides/the-basics/tinybase-and-typescript/">TinyBase And TypeScript</a> guide.</p></section>

```js yolo
const tools = createTools(store);
const [dTs, ts] = tools.getStoreApi('shop');

// -- shop.d.ts --
/* Represents the 'pets' Table. */
export type PetsTable = {[rowId: Id]: PetsRow};
/* Represents a Row when getting the content of the 'pets' Table. */
export type PetsRow = {species: string /* ... */};
//...

// -- shop.ts --
export const createShop: typeof createShopDecl = () => {
  //...
};
```

<section><h2 id="did-we-say-tiny">Did we say tiny?</h2><p>If you use the basic <a href="https://tinybase.org/api/store/"><code>store</code></a> module alone, you&#x27;ll only add a gzipped <em>5.3kB</em> to your app. Incrementally add the other modules as you need more functionality, or get it all for <em>12.7kB</em>.</p><p>The optional <a href="https://tinybase.org/api/ui-react/"><code>ui-react</code></a> module is just <em>4.6kB</em>, the ui-react-dom components are another <em>2.5kB</em>, and everything is super fast. Life&#x27;s easy when you have zero dependencies!</p><p>Read more about how TinyBase is structured and packaged in the <a href="https://tinybase.org/guides/how-tinybase-is-built/architecture/">Architecture</a> guide.</p></section><div class="table"><table class="fixed"><tbody><tr><th> </th><th>Minified .js.gz</th><th>Source .js</th></tr><tr><th class="right"><a href="https://tinybase.org/api/store/">tinybase/store</a> (minimal)</th><td>5.3kB</td><td>52.5kB</td></tr><tr><th class="right">tinybase (complete)</th><td>12.7kB</td><td>130.9kB</td></tr><tr><th class="right"><a href="https://tinybase.org/api/ui-react/">ui-react</a></th><td>4.6kB</td><td>48.3kB</td></tr><tr><th class="right"><a href="https://tinybase.org/api/ui-react-dom/">ui-react-dom</a></th><td>2.5kB</td><td>20.4kB</td></tr></tbody></table></div><section><h2 id="well-tested-and-documented">Well tested and documented.</h2><p>TinyBase has <em>100.0%</em> test coverage, including the code throughout the documentation - even on this page! The guides, demos, and API examples are designed to make it as easy as possible for you to get your TinyBase-powered app up and running.</p><p>Read more about how TinyBase is tested in the Unit <a href="https://tinybase.org/guides/how-tinybase-is-built/testing/">Testing</a> guide.</p></section><div class="table"><table class="fixed"><tbody><tr><th width="30%"> </th><th>Total</th><th>Tested</th><th>Coverage</th></tr><tr><th class="right">Lines</th><td>2,389</td><td>2,389</td><td>100.0%</td></tr><tr><th class="right">Statements</th><td>2,576</td><td>2,576</td><td>100.0%</td></tr><tr><th class="right">Functions</th><td>1,006</td><td>1,006</td><td>100.0%</td></tr><tr><th class="right">Branches</th><td>951</td><td>951</td><td>100.0%</td></tr><tr><th class="right">Tests</th><td colspan="3">6,853</td></tr><tr><th class="right">Assertions</th><td colspan="3">32,079</td></tr></tbody></table></div><hr><section id="sponsors"><h2 id="proud-to-be-sponsored-by">Proud to be sponsored by:</h2><a 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Why trade reactive user experiences to be able to use relational data? Or sacrifice features for bundle size? And why does the cloud do all the work <a href="https://localfirstweb.dev/" target="_blank">anyway</a>?</p><p>Building TinyBase was originally an interesting exercise for <a rel="me" href="https://tripleodeon.com">me</a> in API design, minification, and documentation. But now it has taken on a life of its own, and has grown beyond my wildest expectations.</p><p>It could not have been built without these great <a href="https://tinybase.org/guides/how-tinybase-is-built/credits/#giants">projects</a> and <a href="https://tinybase.org/guides/how-tinybase-is-built/credits/#and-friends">friends</a>, and I hope you enjoy using it as much as I do building it!</p></section><section id="story"><h2 id="the-story">The story</h2><a href="https://youtu.be/hXL7OkW-Prk?t=1232" target="_blank"><img src="https://tinybase.org/youtube.webp"></a></section>