Auth MFE Blog #1 — Introduction, Functional Scope, Technical Scope & React Primer

Beginner-friendly path to a tiny authentication micro-frontend using Vite, React, TypeScript, React Router, and MSW.

Table of Contents

1. #intro — Introduction
2. #functional-scope — Functional Scope
3. #technical-scope — Technical Scope
4. #primer — React Detailed Primer (10-minute)
5. #diagram — Architecture Diagram
6. #prereqs — Prerequisites & Setup
7. #workspace — Create Workspace & First Project
8. #next — What’s next

#intro — Introduction

What is an Auth MFE? An authentication micro-frontend is a small, focused app for login/signup/user-list flows. It can be built and deployed independently, then embedded in larger portals.

Why micro-frontends? They allow teams to ship features faster and independently, avoid risky big releases, and keep codebases smaller and easier to reason about.

Goal of this series: Learn to build a tiny Auth MFE with React + TypeScript + Router, backed by fake APIs using MSW. No real backend needed!

• Blog #1 (this post): scope, tools, React basics.
• Blog #2: implement features in 10 incremental examples.
• Blog #3: add tests and a beginner testing mindset.

#functional-scope — Functional Scope

Features in scope

• /login, /signup, /users (list only)
• Basic navigation
• Fake success/error states
• No real backend (use MSW)

Out of scope

• Security hardening, real tokens
• Persistence
• Design systems

Heads-up: Real apps need token storage and secure flows, but we’ll skip those for now.

#technical-scope — Technical Scope

• Vite — fast dev server and build tool
• React — component-based UI
• TypeScript — safer code with types
• React Router — client-side routing
• MSW — mock API responses

Project anatomy

• index.html — page shell
• src/main.tsx — React entry
• src/App.tsx — routes/layout
• src/pages/* — Login/Signup/Users
• src/mocks/* — MSW handlers

Why MSW? Build UI without waiting for backend. Why TypeScript? Catch errors early. Why Router? Learn SPA mental model.

#primer — React Detailed Primer (10-minute)

• Components: Lego-like UI blocks. function Btn(){ return <button>Click</button> }
• JSX: HTML-like syntax inside JS. const v = (<h1>Hi</h1>)
• State: Memory for dynamic data. const [c,setC]=useState(0)
• Props: Component inputs. <Avatar name="Ada"/>
• Events: Handlers like onClick. <button onClick={fn}>
• Effects: Run side effects. useEffect(()=>{/*fetch*/},[])
• Routing: Map URL→Component. <Route path="/login"/>
• Declarative: Describe UI “what,” not DOM “how.”
• Controlled forms: Input bound to state. <input value={x}/>
• Mocking (MSW): Fake APIs. /api/login -> {"ok":true}
• Beginner testing mindset: Think “what should the user see/do?”

Tip: copy examples, run, tweak. Small wins build confidence!

#diagram — Architecture Diagram

Switch Blogger to HTML mode and add this snippet for Mermaid:

<script type="module">
  import mermaid from "https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.esm.min.mjs";
  mermaid.initialize({ startOnLoad: true });
</script>

flowchart LR
A[React App (Components+Routes)] -- fetch /api/* --> B[MSW Handlers]
B -- returns --> C[(JSON)]
A -- Router --> /login
A -- Router --> /signup
A -- Router --> /users

#prereqs — Prerequisites & Setup

• Node 18+ (20 recommended)
• Git (optional)
• VS Code or IntelliJ

node -v
npm -v
git --version

#workspace — Create Workspace & First Project

# Scaffold project
npm create vite@latest auth-mfe -- --template react-ts
cd auth-mfe
npm install

# Add router + MSW
npm install react-router-dom
npm install --save-dev msw

# Start dev server
npm run dev

Open http://localhost:5173. If port is busy, run npm run dev -- --port=5174.

#next — What’s next

Blog #2: Implement scope step by step (10 examples).
Blog #3: Add beginner-friendly tests.

Mindset: build in tiny steps. Fake it first, real auth later.