```js const authChannel = new BroadcastChannel('authChannel');

authChannel.addEventListener('message', () => { logout(); })

export function logout() { // logout logic }

logoutButton.addEventListener('click', () => { authChannel.postMessage('logout'); logout(); }); ```

```js import { render } from 'solid-js/web'; import { createSignal, For, onCleanup } from 'solid-js';

const todosChannel = new BroadcastChannel('todos');

function Todos() { const listener = todosChannel.addEventListener('message', e => { setTodos(e.data) });

const [todos, setTodos] = createSignal(['One']);

const addTodo = () => { setTodos(todos => [...todos, Math.random().toString()]); todosChannel.postMessage(todos()); }

onCleanup(() => { todosChannel.removeEventListener('message', listener); })

return ( <> <button onClick={addTodo}>Add Todo</button>

  <For each={todos()}>
    {(item) => <div>{item}</div>}
  </For>

) }

render(() => <Todos />, document.getElementById('root')); ```