This repository is a beginner-friendly collection of solved JavaScript interview questions and examples. It focuses on both coding challenges (algorithms, data structures, etc.) and system design problems, giving you ready-to-run JavaScript code and explanations. Each solution file is well-commented to walk you through the logic step by step. For example, an analysis of 100,000+ technical interviews found JavaScript was the third most popular language (used in ~12% of interviews), so practicing these questions can be especially useful.
We also cover system design topics since system design is often included in interviews. In fact, system design is described as “a required component of the technical interview process at many tech companies”, so you can find example design questions here too. Overall, this repo is meant to help you prepare for JavaScript interviews by studying clear examples.
The content is organized by topic into folders. Example folder names include:
coding-challenges/– JavaScript solutions for classic algorithm and problem-solving questions (arrays, strings, sorting, recursion, etc.).data-structures/– Implementations of common data structures (linked lists, stacks, queues, trees) in JavaScript.system-design/– Discussion and example answers for system design questions (e.g., designing a URL shortener or chat server). These problems test high-level design skills often needed in interviews.utils/– (Optional) Utility scripts or helper functions used by examples.
Each folder contains .js files that you can open and read directly. The code in each file includes the question (often in a comment) and a full solution.
You can use this repository without any special setup:
- Clone or download the repo to your computer (
git clone ...or download the ZIP). - Browse folders: Open the folders by topic.
- Open a file: Each
.jsfile contains a problem statement and a JavaScript solution with comments explaining each step. - Run or modify: Optionally, run the code using Node.js or a browser console to see the results. No installation is needed beyond having a JavaScript runtime.
No installation or build is required – just open and explore the files. We recommend trying to solve a problem on your own before reading the solution. Practicing this way will help you learn more effectively and prepare for actual interview questions.
This collection is designed to be helpful whether you’re just starting out or already have some experience:
- Beginners: All solutions include clear comments and explanations. Take your time to read through the code and understand each step.
- Intermediate: Challenge yourself by writing your own solution first, then compare with the provided answer to learn new techniques or optimizations.
Feel free to learn at your own pace. Don’t be afraid to explore the code and ask questions. We hope this resource boosts your confidence and knowledge as you prepare for interviews!
Contributions are welcome! Here are some ways you can help improve this project:
- Add new JavaScript interview questions and solutions.
- Refactor or optimize existing solutions for clarity and performance.
- Fix typos or add more explanations in the comments.
To contribute, simply fork the repository, create a new branch for your changes, and submit a pull request. We appreciate all contributions that make this repo more useful for everyone preparing for JavaScript interviews. Happy coding!