JavaScript Interview Guide

Frontend interviews often ask candidates to do more than recall JavaScript syntax: they may need to reason about promises, implement familiar utilities, or shape a small feature under pressure. JavaScript Interview Guide gathers solved problems around those practical challenges, with a particular focus on JavaScript and frontend development.

Written by Prashant Yadav, the first edition brings together 100 JavaScript questions, 20 React questions, and 2 frontend system-design questions. Short concept sections introduce topics including closures, promises, array methods, functions, and this, giving readers useful context before they work through the problems.

Practice beyond the usual algorithm drill 💻

The JavaScript section ranges across asynchronous programming, data structures, browser APIs, and common utility implementations. Questions include building promise methods, debounce and throttle functions, an LRU cache, a trie, browser history, and a small in-memory search engine. The variety gives readers opportunities to think about how language features and frontend concerns meet in concrete coding tasks.

React hooks and frontend design

React problems include hooks such as usePrevious, useDebounce, and useOnClickOutside, along with interface-oriented tasks. The two system-design problems address a maker-checker flow and an online coding judge. Together, these sections broaden the practice beyond standalone JavaScript functions.

A useful format for focused review

Each question is presented with a solution, making the guide suitable for working through a problem and then comparing approaches. Readers can use it for interview preparation, revisit particular implementation patterns, or choose questions by topic when they want targeted practice. The book is aimed especially at JavaScript and React developers preparing for frontend-focused interviews.

Some problems and solutions are referenced from other sources, as the author notes in the book. Read it as a structured practice collection: try the implementation first, examine the solution, and take time to understand the ideas behind the code.