How often do debounce and throttle appear in real-world JavaScript projects?

For buttons and form submissions, I usually don't rely on debounce or throttle alone. Disable the button while the request is running, then enable it again when the operation finishes. That prevents duplicate submissions and unnecessary backend requests more directly.

Throttle is a better fit when you need updates while an action is still happening, but only at a controlled frequency. Scroll listeners are a common example: checking a sticky header, triggering animations, or loading more content doesn't need to happen hundreds of times per second. Mouse movement and drag interactions can benefit from it too.

Debouncing comes up constantly, especially for search fields, autosave, and resize handlers. If a search box sends a request on every keystroke, debouncing waits until the user pauses before making the call, which cuts down unnecessary network traffic. Resize handlers can use the same approach to recalculate a layout after resizing stops.

I use both, but debounce more often. For search, a delay around 150–300 ms is a reasonable starting point. Be careful with asynchronous requests, though: an older, slower response can arrive after a newer one and overwrite the correct result. Use AbortController or a request ID to ignore stale responses.

They aren't needed everywhere, but they are useful tools whenever an event fires much faster than the work needs to happen. Debounce when only the final value matters, such as after typing stops; throttle when you want periodic updates during the interaction, such as while scrolling. It also helps to understand leading versus trailing execution, since firing immediately and waiting until the end produce different user experiences.