Express is minimal by design — you compose exactly the middleware you need. Today you set up an Express server, define routes for all HTTP methods, write custom middleware, and understand the request/response cycle.
By the end of this lesson you will create an Express server with routes for GET, POST, PUT, and DELETE, write a custom logging middleware, use express.json() and express.urlencoded() for body parsing, and handle 404 with a catch-all route.
Express routing is the foundation of Day 1. Every concept that follows builds on the mental model you establish here. The most effective approach is to understand the principle first, then apply it — skipping straight to implementation creates gaps that compound into confusion later.
Work through each example in this lesson sequentially. The concepts connect, and the order is deliberate. If something is unclear, slow down at that point rather than pushing past it — a ten-minute pause now saves hours of debugging later.
Understanding Express routing requires seeing it in motion. The code below is not a complete application — it is a minimal, working illustration of the key mechanism. Study the pattern, run it, break it deliberately, then fix it. That cycle builds real comprehension.
Once the basic pattern works, the logical next step is middleware. This is where the abstraction becomes useful — you move from understanding the mechanism to applying it to real problems. The transition is usually smaller than it feels. Most of the hard work happened in Section 1.
HTTP methods completes today's picture. It is where Express routing and middleware converge into a pattern you can apply to novel problems. This integration step is often where the day's learning consolidates — if the earlier sections felt abstract, this one typically makes them click.
Implementing Express routing alone handles the happy path. Real systems encounter edge cases, invalid input, and unexpected state. Missing middleware means missing those guards.
Combining Express routing with middleware gives you a complete, defensible implementation. The extra lines cost ten minutes; the robustness they add is worth hours of debugging time.
Several mistakes appear consistently when engineers encounter Routes and Middleware for the first time. Recognizing them now costs nothing; encountering them in production costs hours.
Two intensive days (Thu–Fri) with an instructor who has taught thousands of engineers. Cohorts in 5 cities, June–June–October 2026 (Thu–Fri).
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