StartupJS

    Collection types

    StartupJS organizes data into collections. There are two kinds: public and private.

    Public collections

    Public collections (for example todos, users) are stored in MongoDB and synced across all connected clients. Any change made by one client is broadcast to all others who are subscribed.

    You must subscribe to public collection data before reading it:

    // In a React component (with observer)
const $todos = useSub($.todos, {})

// Outside React
const $todos = await sub($.todos, {})

    Access control is enforced by server rules (see the Security section).

    Private collections

    Private collections exist only on the current client. They are never sent to the server or other clients. Their names start with an underscore.

    • $._session -- persists for the entire browser session (until the tab or app is closed).
    • $._page -- persists only while the current route is active. It resets when the user navigates to a different page.

    You do not need to subscribe to private collections. Read and write them directly:

    $._page.sidebar.opened.set(true)
const isOpen = $._page.sidebar.opened.get()

const userId = $._session.userId.get()

    Use private collections for UI state, temporary data, and any values that do not need to persist in the database.

    Routing parameters

    StartupJS uses Expo Router for file-based routing. Routes are parameterized using bracket syntax in file names. For example: app/pokemon/[pokemonId].tsx.

    To navigate programmatically:

    import { router } from 'expo-router'

router.push('/pokemon/' + pokemonId)

    On the target page, read the parameter with useLocalSearchParams:

    import { useLocalSearchParams } from 'expo-router'

const { pokemonId } = useLocalSearchParams()