CI/CD Pipelines — Complete Guide

CI/CD Pipelines — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of React.js Tutorial on Toolliyo Academy.

8 min read Updated 7/8/2026

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React.js Tutorial · Lesson 90 of 100

CI/CD Pipelines

Beginner ✓ → Intermediate ✓ → Advanced ✓ → Professional

Professional · 4 — ShopCart projects · ~25 min read · Module 9: Testing & Deployment

Introduction

Professional project lesson: CI/CD Pipelines. You will put together routing, data, and UI like a portfolio app. Build one piece at a time — do not rush. CI/CD automatically runs lint, test, and build on every push — then deploys passing builds to staging or production. Manual deploys skip tests and break production. Pipeline enforces quality gates.

A app on your laptop is not finished until it runs somewhere others can open a URL.

When will you use this?

Use when you are ready to put the app online for users or employers to see.

Shipping means tests pass, build succeeds, and Docker or Azure hosts the static files.
Companies run CI so broken code never reaches users.

Real-world: PR gate pipeline

Every pull request runs lint, unit tests, build, and Playwright smoke — merge blocked on failure.

Production-style code

# .github/workflows/pr.yml
jobs:
  verify:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
      - run: npm run lint
      - run: npm test -- --ci
      - run: npm run build
      - run: npx playwright test --grep @smoke

What happens in production: Broken main branch becomes rare — team ships React features with confidence.

Lesson example (start here)

Copy this smaller example first. Once it works, compare it with the real-world code above.

# .github/workflows/ci.yml
on: [push]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
      - run: npm run lint
      - run: npm test
      - run: npm run build

Line-by-line walkthrough

Code	What it means
`# .github/workflows/ci.yml`	Comment — notes for humans; the computer ignores it.
`on: [push]`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`jobs:`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`build:`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`runs-on: ubuntu-latest`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`steps:`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`- uses: actions/checkout@v4`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`- run: npm ci`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`- run: npm run lint`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`- run: npm test`	Part of the CI/CD Pipelines example — read it together with the lines before and after.
`- run: npm run build`	Part of the CI/CD Pipelines example — read it together with the lines before and after.

How it works (big picture)

Every push runs the same checks.
Fail fast on lint or test errors.
Deploy job runs only after build succeeds.

Do this on your computer

Add GitHub Actions workflow file.
Fix lint/test until pipeline green.
Add deploy step with secrets for hosting.
Read the real-world section and name which part of the app uses this topic.
Run the example locally and confirm the same behavior in the browser.
Change one value in the example (text, initial state, or URL) and predict what will happen before you save.

Experiments — try changing this

Change text or labels in the example and save — watch the browser update.
Break the code on purpose (remove a bracket), read the error message, then fix it.

Remember

CI = auto lint + test + build. CD = auto deploy on success. Start with GitHub Actions.

Common questions

CI for solo dev?

Still valuable — catches breaks before users see them.

How long should I spend on CI/CD Pipelines?

Until you can explain it in your own words and run the example without looking at the answer. Beginners often need 30–60 minutes per new hook or routing topic; setup lessons may take one afternoon.

What if I get stuck on CI/CD Pipelines?

Re-read the line-by-line walkthrough, check the browser console for red errors, and compare your code character-by-character with the example. Search the exact error text — someone else had it too.

Where is CI/CD Pipelines used in real jobs?

See the real-world section above — the same pattern appears in LMS, banking, e-commerce, and SaaS products. Interviewers ask you to explain it using one concrete example from your project or this lesson.

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