The Event-Driven Model
Both Node.js and Deno use the same model: single-threaded event loop with non-blocking I/O. The reader learned the event loop in Chapter 17. This section connects it to the server.
A server handles many connections on one thread. I/O operations — file reads, network requests, database queries — are non-blocking. The event loop multiplexes thousands of connections by never waiting for any single one.
Every request handler is an async function. Every I/O operation awaits. The event loop processes events between await points. CPU-intensive work blocks the loop — use Web Workers for that.
The key insight: async/await (Ch 17) is not just syntax sugar for convenience. On the server, it’s how concurrency works. The entire programming model is built on the event loop, and await is the developer’s interface to it.