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Conditional UI and repeated content

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Use Show for one condition, Switch and Match for several alternatives, and For for a short collection. Use Loading and Catch around content that loads or may fail.

Show a signed-in or signed-out view

tsx
import { Button, Show, Text, VStack, signal } from 'kuito';

export function Account() {
  const user = signal<{ name: string } | null>(null);
  return (
    <VStack gap={12}>
      <Show when={user.value} fallback={<Text>Sign in to save your list.</Text>}>
        {(person) => <Text>{`Welcome, ${person.name}`}</Text>}
      </Show>
      <Button onPress={() => (user.value = { name: 'Ada' })}>Try the signed-in view</Button>
    </VStack>
  );
}

A callback child receives the truthy value, so it can safely read person.name. Changing branches mounts the new content and disposes the old content. A JSX ternary also works for simple conditions.

Select one of several states

tsx
import { Match, Switch, Text, signal } from 'kuito';

export function Status() {
  const state = signal<'loading' | 'offline' | 'ready'>('loading');
  return (
    <Switch fallback={<Text>Ready</Text>}>
      <Match when={state.value === 'loading'}>
        <Text>Loading…</Text>
      </Match>
      <Match when={state.value === 'offline'}>
        <Text>Check your connection</Text>
      </Match>
    </Switch>
  );
}

Only the first matching branch renders. Match belongs directly under Switch. The native on/off input is named Toggle.

Render a short checklist

tsx
import { For, Scroll, Text, store } from 'kuito';

export function PackingList() {
  const state = store({ items: [{ title: 'Passport' }, { title: 'Tickets' }] });
  return (
    <Scroll>
      <For each={state.items} fallback={<Text>Add your first item</Text>}>
        {(item, index) => <Text padding={12}>{`${index.value + 1}. ${item.title}`}</Text>}
      </For>
    </Scroll>
  );
}

For renders every item; use List for a feed or large collection. Object identity identifies a row, while primitive items use their values. Reordering existing objects moves their views. index is a signal because the row's position can change.

Coordinate loading and retry

tsx
import { Button, Catch, Loading, Spinner, Text, VStack, resource } from 'kuito';

function Summary() {
  const result = resource(async ({ signal }) => {
    const response = await fetch('https://example.com/api/summary', { signal });
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    return response.text();
  });
  return <Text>{result.data.value ?? ''}</Text>;
}

export function Dashboard() {
  return (
    <Catch
      fallback={(_error, retry) => (
        <VStack>
          <Text>Could not load the summary.</Text>
          <Button onPress={retry}>Retry</Button>
        </VStack>
      )}
    >
      <Loading fallback={<Spinner />}>
        <Summary />
      </Loading>
    </Catch>
  );
}

Loading waits for initial child resources, then keeps the content visible. Later refreshes use each resource's running state. Failures also settle a resource; a Catch or the component itself must display the error.

Catch covers render and lifecycle failures and unhandled automatic resource loads. It does not catch event-handler errors or rejected task.run() and resource.refresh() promises. Handle those where you call them. Retrying a boundary mounts fresh children with fresh state. Put a boundary inside a List row to cover that row's independent rendering scope.