How do you handle networking and API calls?

React Native provides fetch and XMLHttpRequest, both backed by native networking. fetch does not reject on HTTP error statuses, so a 500 response still resolves. A robust client checks response.ok and parses errors deliberately.

export async function getJson<T>(url: string, signal?: AbortSignal): Promise<T> {
  const controller = new AbortController();
  const timeout = setTimeout(() => controller.abort(), 10000);
  const combined = signal ?? controller.signal;

  try {
    const response = await fetch(url, {
      headers: { Accept: "application/json" },
      signal: combined,
    });

    if (!response.ok) {
      throw new Error("Request failed with status " + response.status);
    }

    return (await response.json()) as T;
  } finally {
    clearTimeout(timeout);
  }
}

What belongs in the data layer

• Base URL and auth header injection in one place
• Timeout, cancellation and retry policy with exponential backoff
• Response validation at the boundary
• Cache policy and invalidation through a query library
• Error normalisation so the UI can distinguish offline from server errors

On mobile, connectivity is intermittent. A request may fail because the radio is asleep, the user moved between networks, or the app was backgrounded. Treat failure as normal, show a retry affordance, and cancel in-flight requests when a screen unmounts to avoid state updates after navigation.