Middleware Chain
ELI5 — The Vibe Check
A middleware chain is a series of functions that requests pass through, one after another, like an assembly line. Each middleware does its thing — log, authenticate, validate — and passes the request to the next one. The order matters: you authenticate before you authorize.
Real Talk
A middleware chain is the sequential execution of middleware functions in a defined order. Each middleware receives the request, response, and a next() function to pass control to the subsequent middleware. The chain can be short-circuited (by sending a response early) or modified (by adding data to the request). The order of registration determines execution order.
When You'll Hear This
"The middleware chain runs: logging → CORS → auth → validation → handler." / "If auth middleware rejects the request, the handler never runs."
Related Terms
Express
Express is the most popular framework for building Node.js backends.
Middleware
Middleware is like a security checkpoint at an airport.
Pipeline Pattern
The pipeline pattern processes data through a series of stages, where each stage transforms the data and passes it to the next.
Request Lifecycle
The request lifecycle is the journey your HTTP request takes from the moment it hits the server to when a response goes back.