Ace the JavaScript interview

The handful of topics that come up in almost every front-end interview, and how to talk about them with confidence.

Interviews rarely test obscure trivia. They test whether you understand the few mechanics that the whole language rests on.

Get comfortable explaining these out loud and most questions become variations on a theme.

The short list

Closures: why a returned function still remembers its scope.
The event loop: how promises and timers actually get scheduled.
this: how it is decided at call time, not at definition time.
Prototypes: what really happens on a property lookup.

For example, a closure is not magic. The returned function still has access to the lexical scope where it was created:

function createCounter(start = 0) {
  let value = start;

  return function increment() {
    value += 1;
    return value;
  };
}

const next = createCounter(10);

console.log(next()); // 11
console.log(next()); // 12

Practice narrating your reasoning, not just reciting the answer. An interviewer learns far more from "here is how I would reason about it" than from a memorized definition.

Placeholder article: the full write-up with runnable examples is coming soon.