Function isServerLoader

Server data-loading API for React pages, re-exported from @stone-js/use-view.

A page's handle(event) is its loader. For fine control over the SSR ⇄ CSR boundary — e.g. fetching authenticated data from an API during SSR with the request token, and degrading gracefully when it fails — wrap the fetch in a server loader:

import { defineServerLoader, runServerLoader, createServerLoaderContext } from '@stone-js/use-react'

const loadUser = defineServerLoader(async ({ token, fetch }) => {
  const res = await fetch('/api/me', { headers: { authorization: `Bearer ${token}` } })
  if (!res.ok) throw new Error('unauthorized')
  return res.json()
}, { policy: 'server-first' }) // try on the server; on failure, defer to the client

class ProfilePage implements IPage<ReactIncomingEvent> {
  async handle (event: ReactIncomingEvent) {
    const ctx = createServerLoaderContext({
      event,
      isServer: typeof window === 'undefined',
      cookies: event.get('cookies', {}),
      tokenCookieName: 'session'
    })
    const outcome = await runServerLoader(loadUser, ctx)
    return outcome.data // undefined when deferred/given-up → the component renders a loading/empty state
  }
}
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