Hiring Guide

Top 50 TypeScript Interview Questions and Answers + PDF

Comprehensive interview preparation guide featuring advanced TypeScript concepts, real-world scenarios, and expert-vetted answers. Perfect for senior developers preparing for technical interviews or engineering managers building assessment frameworks.

Core Concepts
Data Structures and Algorithms
System Design
Coding and Debugging
Behavioral Questions

Identify Top 5% TypeScript Talent

Used by leading tech companies to filter candidates who truly understand type systems, advanced patterns, and production-grade TypeScript development.

Start hiring now

Core Concepts

Data Structures and Algorithms

System Design

Coding and Debugging

Behavioral Questions

Hire Pre-Vetted TypeScript Experts

Skip the screening process. Index.dev connects you with senior TypeScript developers who've already passed rigorous technical assessments. Reduce time-to-hire by 60% while accessing the top 5% of global talent.

Scale Smart

Interview Questions for Other Related Skills

React Native Coding Challenges

MongoDB Coding Challenges

Ruby on Rails Coding Challenges

Computer Vision Engineer

DBT Developer

Why Index.dev?

Our talent is hand-picked

Work with only the best 5% developers worldwide.

We prioritize speed

Start interviewing qualified candidates within 48 hours.

We respect your budget

Get senior talent at 50% less than competitors with built-in compliance.

Top 50 TypeScript Interview Questions and Answers + PDF

Identify Top 5% TypeScript Talent

Core Concepts

Explain the difference between 'type' and 'interface' in TypeScript. When would you choose one over the other?

What are conditional types in TypeScript? Provide a practical example of their usage.

Explain mapped types and provide an example of creating a deep partial type.

What is the 'infer' keyword and how does it work in TypeScript?

How do template literal types work? Provide an example of building a type-safe event system.

Explain variance in TypeScript. What are covariance, contravariance, and bivariance?

What are discriminated unions and how do they enable exhaustive type checking?

How do you implement a type-safe builder pattern in TypeScript?

Explain the difference between 'unknown' and 'any'. When should you use each?

What are const assertions and how do they differ from regular const declarations?

Data Structures and Algorithms

How would you implement a generic Stack data structure in TypeScript with type safety?

Implement an LRU (Least Recently Used) Cache with O(1) get and put operations in TypeScript.

How do you find all pairs in an array that sum to a target value? What's the optimal time complexity?

Implement a type-safe Binary Search Tree with insert, search, and inorder traversal methods.

Implement a sliding window algorithm to find the maximum sum of k consecutive elements in an array.

How would you implement a Queue using two Stacks in TypeScript? What are the time complexities?

Implement a function to detect if a linked list has a cycle using Floyd's algorithm. Include TypeScript types.

How do you implement a Trie (Prefix Tree) for efficient string searching? Include insert and search methods.

Implement a Min Heap with insert and extractMin operations. What are the time complexities?

How would you implement a function to find the longest substring without repeating characters? Optimize for time complexity.

System Design

Design a scalable URL shortener service like bit.ly. What are the key components and how would you handle high traffic?

Design a real-time chat application supporting millions of concurrent users. How would you handle message delivery, presence, and scalability?

Design a distributed rate limiter that can handle 100k requests per second. Discuss algorithms, data structures, and implementation challenges.

Design a news feed system like Twitter or Facebook. How would you generate, rank, and deliver personalized feeds to millions of users?

Design a distributed cache system. How would you handle cache invalidation, consistency, and high availability?

Design a video streaming platform like YouTube. How would you handle video upload, transcoding, storage, and adaptive streaming?

Design an e-commerce inventory management system that handles high concurrency. How would you prevent overselling and maintain consistency?

Design a notification system that supports push notifications, emails, and SMS across millions of users. How would you ensure delivery and handle failures?

Design a ride-sharing service like Uber. Focus on the matching algorithm, location tracking, and handling high concurrency during peak hours.

Design a search engine autocomplete system. How would you handle billions of queries, provide sub-100ms latency, and update suggestions in real-time?

Coding and Debugging

Write a TypeScript function to flatten a nested array of any depth with proper type safety.

How do you implement a type-safe event emitter in TypeScript with strict event typing?

Write a function to check if a string is a palindrome, optimized for performance with TypeScript.

How do you debug memory leaks in TypeScript applications? What tools and techniques do you use?

Implement a debounce function in TypeScript with proper typing for any function signature.

What are TypeScript decorators and how would you implement a method execution timer decorator?

How do you handle and debug 'Type instantiation is excessively deep' errors in TypeScript?

Implement a type-safe deep partial utility type that works with nested objects and arrays.

What techniques would you use to debug TypeScript compilation errors in large codebases?

How would you implement monkey patching safely in TypeScript while maintaining type safety?

Behavioral Questions

Tell me about a time when you had to refactor a large JavaScript codebase to TypeScript. What was your approach?

Describe a situation where TypeScript's type system prevented a critical bug. How did you handle it?

Give an example of when you had to convince your team to adopt advanced TypeScript features like generics or conditional types.

Tell me about a time when you had to balance type safety with development speed. What trade-offs did you make?

Describe a challenging debugging experience involving TypeScript's type inference. How did you resolve it?

Tell me about a time when you improved the developer experience using TypeScript's tooling or configuration.

Describe a situation where you had to work with poorly typed third-party libraries. What was your solution?

Give an example of when you had to mentor junior developers on TypeScript best practices. What was your approach?

Tell me about a time when you had to optimize TypeScript compilation performance in a large project.

Describe a situation where you had to make architectural decisions involving TypeScript in a microservices environment.

Hire Pre-Vetted TypeScript Experts

Interview Questions for Other Related Skills

Why Index.dev?

Our talent is hand-picked

We prioritize speed

We respect your budget

Top 50 TypeScript Interview Questions and Answers + PDF

Identify Top 5% TypeScript Talent

Core Concepts

Explain the difference between 'type' and 'interface' in TypeScript. When would you choose one over the other?

What are conditional types in TypeScript? Provide a practical example of their usage.

Explain mapped types and provide an example of creating a deep partial type.

What is the 'infer' keyword and how does it work in TypeScript?

How do template literal types work? Provide an example of building a type-safe event system.

Explain variance in TypeScript. What are covariance, contravariance, and bivariance?

What are discriminated unions and how do they enable exhaustive type checking?

How do you implement a type-safe builder pattern in TypeScript?

Explain the difference between 'unknown' and 'any'. When should you use each?

What are const assertions and how do they differ from regular const declarations?

Data Structures and Algorithms

How would you implement a generic Stack data structure in TypeScript with type safety?

Implement an LRU (Least Recently Used) Cache with O(1) get and put operations in TypeScript.

How do you find all pairs in an array that sum to a target value? What's the optimal time complexity?