React, revised in a day
Everything a senior React interview asks — in plain language, with short examples you can edit and run right on the page. 15 modules, 115 questions, and a quick-recap cheat sheet for the last hour before the call.
Modules
How to use this
Read a module top to bottom (10–15 minutes each). Don't memorise the long text — read the In one line box, look at the example, then read the 30-second interview answer out loud. That last box is what you actually say in the interview.
| If you have… | Do this |
|---|---|
| 2 days | Modules 00–07 on day one, 08–14 on day two. Flashcards each evening. |
| 1 day | Modules 00, 03, 04, 05, 09, 12, 14 (the ones interviewers dig into), then the cheat sheet. |
| 2 hours | Cheat sheet → flashcards → skim the Trap boxes only. |
| 30 minutes | Cheat sheet, printed. Read the bold parts twice. |
The live examples
Every example is editable. Change the code and press Run (or
Ctrl+Enter); press Reset to get the original back. Anything you
console.log appears under the output — useful for seeing exactly when
useEffect fires.
Examples use React.useState instead of an import, because there is no build step
here — everything runs in the browser. In a real project you would write
import { useState } from "react". Every example must define a component called
App; that is the one that gets rendered.
What's covered
Your 80 questions, grouped into 15 modules, plus Module 00 on how a React
project is actually wired (index.html → main.tsx →
App.tsx, providers, Vite structure) and a Senior Extras module with the
topics interviewers commonly add on top: useReducer, React 19, stale closures,
fetch race conditions, StrictMode, testing and folder architecture — plus dedicated coverage of
MSAL with Authorization Code + PKCE (Module 10),
React Hook Form with zod (Module 7) and a full
TanStack Query module (Module 14) whose examples run the real library.
Type in the search box at the top of the sidebar (try "memo", "key", "token") to jump straight to any question from any page.