Testing, Performance & Production covers: Node.js High Performance, JavaScript Masterclass. Master JavaScript testing strategies (unit, integration, E2E), bundle optimization, runtime performance, Core Web Vitals, monitoring, error tracking, and production deployment. Move from "it works in development" to "it works reliably at scale."
Jest is RSpec for JavaScript. React Testing Library is like Capybara for components — it encourages testing behavior, not implementation. describe/it/expect in Jest matches describe/it/expect in RSpec. screen.getByRole("button") is like find_button in Capybara. Cypress is like system tests but running in a real browser with time-travel debugging. The testing philosophy is the same: test behavior, not implementation; write tests that give you confidence, not tests that test the framework. Bundle optimization has no Rails equivalent — in Rails, the asset pipeline handles everything; in JavaScript, you must actively manage what gets shipped to the browser.
This course unlocks once you've finished its prerequisite. Open prerequisite →
Testing in JavaScript is a mess compared to RSpec, and I will not pretend otherwise. In Ruby, you have RSpec. Maybe Minitest. Two options, clear winner, community consensus. In Ja…
Here is the trap waiting for every Rails engineer who ships a Node service: in Rails, one slow request occupies one Puma thread and the other threads keep serving traffic. In Node…
You have thousands of RSpec examples behind you. You know, in your bones, what a trustworthy test suite feels like — and that is exactly why frontend testing will initially offend…
Work through each item before the checkpoint.
Take your Course 4 (Mission Control) or Course 6 (Reading Log) fork and make it production-grade. This checkpoint is reviewed by your mentor against your repo and audit notes; the…
5 lessons. Read in order; spiral back when you need to. By the end you'll have used the core ideas twice — once on the abstract, once on something you'll meet at work next week.