Memo, refs, suspense, server components: production React.
Questions
15
Tier
Advanced
Language
React
Time
~20 min
Difficulty mix: 2 easy, 7 medium and 6 hard. The questions are drawn from the React library at the moment you start, so sitting the test twice does not give you the same paper.
What this test can pull from
42 React topics are in scope. These are the real topic labels on the questions.
useEffect dependency arrays
function components
what JSX is
embedding expressions
reconciliation diffing
custom hooks
lazy and Suspense
context and useContext
concurrent rendering tearing
forwardRef
useReducer
controlled vs uncontrolled
Server Components use client
fiber and lane priorities
render vs commit phase
React Router v6
hydration mismatches
React.memo bailout
bundler internals webpack vite
Server Actions
props read-only
useMemo
useCallback
useEffect vs useLayoutEffect timing
derived vs stored state
StrictMode double-invoke
automatic batching
stale-closure pitfalls
lifting state up
useSyncExternalStore
Questions of the kind this test asks
Six real React questions from the same pool, snippet included. The answer options and explanations are not shown here. Those come after you attempt them.
// this has nothing to do with question, it's a test question
const Abc = () => {
const [a, v] = useState("abc");
return (
<div>
new abc
dkkdkd
<span>
Nice working
</span>
</div>
)
}