debounce and throttle

Learn debounce and throttle.

debounce: waits until the stream goes quiet, then forwards the last element. Used in search boxes to avoid hitting the server on every keystroke.

throttle: forwards at most one element per period, dropping the rest. Ideal for squashing scroll and resize events.

Both exist in the rxdart package as debounceTime and throttleTime. In pure Dart they can be written by hand with timers and asyncExpand.

Simple throttle: take

.take(n) takes the first n elements of a stream and drops the rest. This is the simplest throttle form: a count-based limit instead of time-based.

Example: Stream.fromIterable([1, 2, 3, 4]).take(2) forwards only 1 and 2; 3 and 4 are never produced (lazy stream).

For real time-based throttling use rxdart's throttleTime or a custom timer-based transformer.

Make main async. Add var s = Stream.fromIterable([1, 2, 3, 4]);. Add await s.take(2).forEach(print);.

Show example solution

void main() async {
  var s = Stream.fromIterable([1, 2, 3, 4]);
  await s.take(2).forEach(print);
}