TypeScript coding interview practice

A TypeScript interview is a JavaScript interview with a second question running alongside it: can you describe your data precisely? The types are part of the answer, so they are also part of what gets scored.

How do I practise a TypeScript coding interview?

To practise a TypeScript coding interview, solve the problem as in JavaScript, then type it well: interfaces for nodes and results, generics for reusable helpers, strict null checks around Map.get, and narrowing instead of casts. Interviewers read your types as evidence that you understand the data.

Practise a TypeScript interview

What interviewers expect in TypeScript

Start by declaring the shapes: a tree node, a graph as a Map from a node to its neighbours, a result object. Precise types make the rest of the code easier to reason about, and speaking them aloud doubles as clarifying the problem.

Expect questions that go one level below the syntax: the difference between interface and type, why a union is safer than any, what strictNullChecks catches, and when a generic helps. Keep answers short and concrete.

TypeScript tools worth knowing cold

Map<K, V> and Set<T> carry their element types; Map.get returns V | undefined, so handle the missing case or state why it cannot happen. Record<string, T> and Partial<T> cover common object shapes.

Interfaces describe nodes and API results; discriminated unions model states; generics type helpers such as a heap or a memoise function without losing information.

Narrowing with typeof, in, equality checks and early returns turns a union into a usable type without assertions. Use readonly and as const when data should not change.

Everything from JavaScript still applies: comparator-based sorting, no built-in heap, the safe integer range and === over ==.

TypeScript mistakes that cost points

Reaching for any or a non-null assertion (the ! operator) to silence the compiler. It hides exactly the bug the type system found; say what guarantees the value exists, or handle it.

Casting with as to force a shape instead of narrowing, which moves the error from compile time to run time.

Overengineering the types. A clear interface and one generic usually beats a clever conditional type in a timed interview.

Forgetting that types disappear at run time: you cannot test an interface with instanceof, so use a discriminant field or a type guard.

Inheriting the JavaScript traps: Array.sort without a comparator sorts as strings, and large integers lose precision.

Practising TypeScript here

On giveinterview you practise TypeScript in the format you will face: you explain your approach first, write the solution in a live editor that runs TypeScript, and then the interviewer asks cross-questions about edge cases, complexity and a changed constraint. The session ends with a scored report that shows whether you lost points explaining, coding or defending.

Your first 3 single-question interviews are free for life, every interview report is free, and a new account also gets 6 welcome credits. After that a single-question interview costs 1 credit, and credits do not expire.

Frequently asked questions

Is TypeScript accepted in coding interviews?

Often yes, especially for front-end, full-stack and Node roles. Check the role description; if it is silent, ask or use JavaScript.

Do types slow me down in a timed round?

A little at the start, and they save time debugging later. Keep them simple and add detail only where it clarifies the data.

Can I run TypeScript here?

Yes. The live editor runs TypeScript, so you can type and test your solution during the interview.