Debouncing refers to cleaning up the signal from an opening and closing switch contact so that the cleaned signal matches the intended semantics of the switch action (e.g. one simple press of a button, not fifty pulses).

The analogy here is poor; reducing thrashing in those obnoxious search completion interfaces isn't like debouncing.

Sure, if we ignore everything about it that is not like debouncing, and we still have something left after that, then whatever is left is like debouncing.

One important difference is that if you have unlimited amounts of low latency and processing power, you can do a full search for each keystroke, filter it down to half a dozen results and display the completions. In other words, the more power you have, the less important it is to do any "debouncing".

Switch debouncing is not like this. The faster is your processor at sampling the switch, the more bounces it sees and consequently the more crap it has to clean up. Debouncing certainly does not go away with a faster microcontroller.

One thing to watch out for when using debounce/throttle is the poor interaction with async functions. Debounced/throttled async functions can easily lead to unexpected behavior because they typically return the last result they have when the function is called, which would be a previous Promise for an async function. You can get a result that appears to violate causality, because the result of the promise returned by the debounce/throttle will (in a typical implementation) be from a prior invocation that happened before your debounce/throttle call.

There are async-safe variants but the typical lodash-style implementations are not. If you want the semantics of "return a promise when the function is actually invoked and resolve it when the underlying async function resolves", you'll have to carefully vet if the implementation actually does that.

I recently wrote a bit about debouncing fetch using timeouts and AbortController, including small demos, here: https://thomascountz.com/2025/07/02/debouncing-api-calls

Debounce -> Like when we throw a ball once on ground, but it keeps bouncing, To prevent that

Human interaction with circuits, sensors, receptors, occur like that

When we click a keyboard key or switch circuit switch the receptors are very sensitive

we feel we did once but during that one press our fingers hands are vibrating multiple times hence the event get registered multiple times due to pulsating, hence all after first event, the second useful event that can be considered legitimate if the idle period between both matches desired debounce delay

in terms of web and software programming or network request handling

it is used as a term to debounce to push away someone something aggresive

Example wise

a gate and a queue Throttling -> gate get opened every 5 min and let one person in, no matter what

Debounce -> if the persons in queue are deliberately being aggressive thrashing at door to make it open we push them away Now instead of 5 min, we tell them you have to wait another 5 min since you are harassing, if before that they try again, we again tell them to wait another 5 min Thus debounce is to prevent aggresive behaviour

In terms of say client server request over network

We can throttle requests processed by server, let say server will only process requests that happen every 5 min like how apis have limit, during that before 5min no matter how many request made they will be ignored

But if client is aggressive like they keep clicking submit button, keep making 100s of requests that even after throttling server would suffer kind of ddos

so at client side we add debounce to button click event

so even if user keep clicking it being impatient, unnecessary network request will not be made to server unless user stop

I think it's a fitting analogy. Depends on the intended behaviour, really.

That said, this is a good resource on the original meaning: https://www.ganssle.com/debouncing.htm

I've always used the term Coalescing in the past: https://en.wikipedia.org/wiki/Coalescing_(computer_science)

I needed an implementation of debounce in Java recently and was surprised to find out that there's no existing decent solution - there's none from the standard library, nor popular utilities libraries like Guava or Apache Commons. There are some implementations floating around like on Stackoverflow but I found them lacking, either there's no thread safety or there's no flexibility in supporting the execution of the task at the leading edge or trailing edge or both. Anyone has a good recommendation on a good implementation?

Not sure if anyone else has noticed, but this has been a super popular interview question for front end interviews.