How should you handle fast typing in a JavaScript search bar?

Debouncing is the main way to reduce unnecessary API traffic. AbortController is useful for requests that have already started, but it does not prevent the initial request from being sent. Debouncing alone also does not completely prevent out-of-order responses, so the UI should still ignore results from older searches.

Use both techniques because they solve different problems. Debounce the input by roughly 300 ms so a request is sent only after the user pauses typing. When a new search begins, use an AbortController to cancel the previous fetch. Also track a sequence number or request ID and update the interface only when the response belongs to the latest search. That final check protects you if cancellation happens too late or the server response has already arrived.

Think of the two issues separately: if the goal is to avoid hitting the server on every keystroke, debounce the input; if the goal is to prevent stale results from appearing, cancel earlier requests or compare request timestamps or IDs before updating the UI. In practice, combining both gives the most reliable behavior.