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 event-loop.md.
• “Why is this undefined here?” — method extraction / arrow vs function. See this-and-binding.md.
• “Make this lazy / stream it” — generators and for await...of. See generators-and-iterators.md.
• “This app leaks memory — find it” — listeners/timers/detached DOM, heap snapshots. See memory-and-gc.md.
• “Why didn’t your try/catch catch that?” — async error propagation. See errors.md.

Cross-references

• TypeScript (types over this language core): ../04_typescript/
• Browser internals / rendering pipeline: ../18_browser_internals/
• Data fetching, AbortController, race conditions: ../11_apis_data_fetching/
• ES2020+ syntax features: ../13_es_features/

External resources

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

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