Debounce

Debounce works like "wait until you stop." Every keystroke fires an input event, and if each one calls the API, typing one word sends several requests. With a 300ms debounce, each new event restarts the timer, and the request only goes out once the user has stopped typing for a full 300ms.

Good fits: search suggestions, checking whether a username is taken as you type, recalculating the layout after a window resize ends, and autosaving drafts.

It's easy to confuse with Throttle. Debounce "runs once after you stop," and doesn't run at all during continuous activity. Throttle "runs at a fixed interval," so it runs several times on a steady beat during continuous activity. Rule of thumb: if you only care about the final result, use debounce; if you need ongoing feedback along the way, use throttle.