Node.js
An event-driven runtime built for I/O-bound workloads and concurrent connection handling.
Node.js is my primary runtime for API servers, real-time services, and backend tooling. Its single-threaded event loop model is genuinely well-suited for I/O-bound workloads. The hard part isn't the runtime — it's preventing structural decay as the codebase accumulates logic without clear layer boundaries.
My Node.js codebases are structured in explicit layers — routes, controllers, services, and data access — with dependencies injected manually rather than through a framework container. This keeps the dependency graph visible and makes unit tests tractable without standing up a full application context. Error propagation follows a consistent pattern: typed error classes at the domain boundary, centralized Express error middleware, and no swallowed rejections. When I inherit an existing JS codebase, I start the TypeScript migration by enabling allowJs and checkJs in tsconfig without moving a single file. That surfaces real type errors with zero disruption. From there I ramp strict mode settings incrementally — strictNullChecks first, then noImplicitAny — and convert files to .ts one module at a time, prioritizing the service and data layers before touching route handlers. For performance work, I run clinic.js doctor first to get a categorized read on event loop delay, CPU saturation, and memory pressure. If doctor points to event loop blocking, I use node --prof to generate a V8 tick profile and convert it to a flame graph with node --prof-process or 0x. That usually surfaces a synchronous operation — JSON.parse on a large payload, a sync fs call, a poorly written middleware — sitting on the hot path. I fix blocking at the source rather than moving work off-thread unless the computation genuinely warrants a worker.
Codebase Structure Review
I map the existing layer boundaries — or the absence of them — looking specifically at where business logic leaks into route handlers, how errors are propagated and where they're silently swallowed, and whether the test suite requires full application context to run a single unit. The output is a concrete, prioritized refactor plan.
TypeScript Migration
I start by adding allowJs and checkJs to tsconfig so the compiler flags real type errors without touching any file extensions. From there I ramp strictness incrementally — strictNullChecks, then noImplicitAny — and migrate modules to .ts one at a time, working inward from the data layer rather than starting at the routes.
Performance Profiling
I start with clinic.js doctor to classify the problem: event loop delay, CPU saturation, or memory growth. For event loop blocking, I use node --prof to collect a V8 tick profile and 0x to render it as a flame graph. That typically identifies the specific function or middleware sitting synchronously on the hot path, which I then fix at the source.
Real-Time APIs
WebSocket servers and Server-Sent Event streams where the event loop model maintains high concurrent connection counts without a thread-per-connection overhead. Node's non-blocking I/O makes this a natural fit rather than an optimization problem.
BFF (Backend for Frontend)
A thin Node.js layer that fans out requests to multiple upstream services, normalizes response shapes, and enforces the contract between backend APIs and frontend clients. Keeps API aggregation logic out of the browser and out of the core backend services.
Build Tooling & Scripts
Custom build scripts, AST transforms, code generators, and file-system automation where Node's ecosystem coverage and native cross-platform path handling make it more practical than shell scripting.
Let's talk Node.js.
No pitch. Just a technical conversation about the problem you're working on.