#javascript

8 javascript interview questions, asked at Apple, Amazon, Waymo and 1 more company. Last asked Sep 2026.

Autocomplete search bar with a hand-written debounceCodingBuild an autocomplete search bar: as the user types, show suggestions for the current text, fetched from a suggestion service. Calls must be debounced, so the service is called…
Last asked Sep 2026
JavaScript let versus varCodingPredict what short JavaScript snippets print and explain the difference between let and var: scope, hoisting, and how each behaves in loops and closures.
Last asked Aug 2026
JavaScript scope, closures, timers and the event loopCodingA frontend fundamentals round: predict what short JavaScript snippets print and explain why. Expect scope (var versus let, hoisting), closures (including the classic loop with…
Last asked Jul 2026
Run promise tasks with bounded concurrencyCodingGiven a list of async tasks (functions returning promises) and a limit k, run them with at most k in flight at once, start the next as soon as one finishes, and resolve with all…
Last asked May 2026
Implement debounceCodingWrite debounce(fn, wait), which returns a function that delays calling fn until wait milliseconds have passed since the last call. Keep this and the arguments of the last call…
Last asked Feb 2026
Implement an event emitterCodingImplement an event emitter class: on(event, handler), off(event, handler), once(event, handler) and emit(event, ...args). Handlers run in the order they were added. Handle a…
Last asked Jan 2026
Deep clone an objectCodingWrite a function that makes a deep copy of a value that can contain nested objects and arrays, so changing the copy never changes the original. Talk through which types need…
Last asked Sep 2025
Debounce and throttle in JavaScriptCodingImplement debounce(fn, wait) and throttle(fn, wait) in JavaScript. Keep this and the arguments of the latest call, support cancelling, and discuss options to fire on the leading…
Last asked Sep 2025