Most TypeScript projects barely scratch the surface of what the type system can enforce at compile time. This post walks through four real-world patterns using conditional types, mapped types, and the infer keyword that eliminate entire categories of runtime bugs.
A cache write is missing, a database row is corrupted, a WebSocket state machine is stuck in limbo. These are not flaky infrastructure problems. They are JavaScript race conditions, and they follow predictable patterns. Here is how to spot, reproduce, and fix the five most common async race patterns in Node.js and the browser.
Fire off 10,000 concurrent API calls and you get rate-limited, OOM-killed, or both. Batch them with Promise.all and one slow item blocks the whole batch. Here is the promise-pool pattern with backpressure and abort signals that gives you full control over concurrent async work.
Your order-fulfillment code is a tangle of boolean flags, if-else chains, and silent failure paths. Replace it with an explicit state machine that is testable, auditable, and survives server restarts.