Why do this? In JavaScript, arrays and objects are passed by reference, so this practice ensures changes won't affect other code that might hold references to the same data. Furthermore, the Gutenberg project follows the philosophy of the Redux library that [state should be immutable](https://redux.js.org/faq/immutable-data#what-are-the-benefits-of-immutability)—data should not be changed directly, but instead a new version of the data created containing the changes.

The `save` function defines the way in which the different attributes should be combined into the final markup, which is then serialized into `post_content`.

// Do not add new properties here, use `useDispatch` instead to avoid

// leaking new props to the public API (editor.BlockListBlock filter).

return {

const { getMultiSelectedBlockClientIds } =

registry.select( blockEditorStore );

const multiSelectedBlockClientIds =

getMultiSelectedBlockClientIds();

const clientIds = multiSelectedBlockClientIds.length

? multiSelectedBlockClientIds

: [ clientId ];

updateBlockAttributes( clientIds, newAttributes );

},

// because updates are batched after the render and changes in different query properties

// would cause to override previous wanted changes.

const updateQuery = useCallback(

);

useEffect( () => {

const newQuery = {};