// Async callbacks - deterministic demo // Define callback type shape (JS comment for parity with TS example) // type FetchCallback = (error: Error | null, data?: string) => void function fetchDataWithCallback(url, callback) { // Deterministic: always succeeds quickly setTimeout(() => { callback(null, 'RESPONSE DATA'); }, 0); } fetchDataWithCallback('https://api.example.com', (error, data) => { if (error) { console.log('ERROR:', error.message); return; } console.log(data); });