JavaScript Core — Senior Interview Prep

Language fundamentals through the lens of “explain what your code actually does.” The numbered senior top-ups (event loop, this, prototypes, generators, modules, memory, errors) cover what post-2022 interviews probe beyond closures and array methods.

Files

Fundamentals

Functions, objects, this

Async

Memory & errors

How an interviewer probes JS core depth

• “What’s the output?” — event-loop ordering of sync / microtask / macrotask. See The Event Loop — Macrotasks, Microtasks, Rendering.
• “Why is this undefined here?” — method extraction / arrow vs function. See this and Binding.
• “Make this lazy / stream it” — generators and for await...of. See Generators and Iterators.
• “This app leaks memory — find it” — listeners/timers/detached DOM, heap snapshots. See Memory and Garbage Collection.
• “Why didn’t your try/catch catch that?” — async error propagation. See Errors and Error Handling.

Cross-references

• TypeScript (types over this language core): TypeScript — Senior Interview Prep
• Browser internals / rendering pipeline: Browser Internals — Senior Interview Prep
• Data fetching, AbortController, race conditions: APIs & Data Fetching — Senior Interview Prep
• ES2020+ syntax features: Modern ES Features — Senior Interview Prep

External resources

Saved question banks (general-purpose; the notes above go deeper):

• InterviewBit — JavaScript
• GeeksforGeeks — JavaScript
• sudheerj/javascript-interview-questions
• BuiltIn — JavaScript
• Simplilearn — JavaScript