Lesson 3 — A CI pipeline

Steps that stop on failure

CI (continuous integration) is a server that runs your checks on every change: install, lint, test, build. The steps run in order, and the first failing step stops the pipeline — there is no point building code whose tests fail. GitHub Actions and GitLab CI work like this.

Note: real DevOps tools (CI servers, load balancers, Docker, Kubernetes) cannot run in your browser, so this exercise is a small plain-JS simulation of the logic those tools use. Each step is a function that returns true (passed) or false (failed).

Why it matters: a red pipeline stops broken code before it reaches users.