JavaScript · recruiter script
JavaScript screening questions for recruiters
Screening a JavaScript developer without coding yourself. These questions expose real understanding of how the language behaves.
1. Explain the difference between `let`, `const`, and `var`.
- Junior
- `const` cannot be reassigned; `let`/`var` can.
- Senior
- Block vs function scope, hoisting, temporal dead zone; defaults to const.
- Red flag
- Still uses `var` everywhere and cannot explain scope.
2. What is the event loop, and why is JavaScript called non-blocking?
- Junior
- Handles async callbacks so code does not freeze.
- Senior
- Call stack, task/microtask queues, promises resolve before timers; single-threaded model.
- Red flag
- Thinks JavaScript is multithreaded or cannot explain async at all.
3. What is a closure, and give a practical use for one.
- Junior
- A function that remembers variables from where it was created.
- Senior
- Lexical scope capture; use for private state, memoization, callbacks.
- Red flag
- Cannot define it or give an example.
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