#promises

Master async programming. Patterns: 1. async/await for readability. 2. Promise.all for parallel execution. 3. Promise.allSettled for all results. 4. Promise.race for timeout handling. 5. Try/catch for error handling. 6. Avoid callback hell. 7. Handle unhandled rejections. 8. Sequential vs parallel trade-offs. Use for I/O operations. Don't block event loop. Implement retry logic for resilience.

Explain how `async` and `await` work in JavaScript for handling asynchronous operations. How do they differ from using `.then()` with Promises? Provide a code example that fetches data from an API, first using Promises with `.then()` and then refactored to use `async/await`.