debouncer.dart

import 'dart:async';

class Debouncer {
  final Duration delay;
  Timer _timer;

  Debouncer({this.delay});

  run(Function action) {
    _timer?.cancel();
    _timer = Timer(delay, action);
  }
}

debouncer_usage.dart

// to start
final _debouncer = Debouncer(delay: Duration(milliseconds: 250));

// and later
onTextChange(String text) {
  _debouncer.run(() => print(text));
}

Slight modification based on my preference.

class Debouncer {
  final Duration delay;
  Timer _timer;

  Debouncer({this.delay = const Duration(milliseconds: 300)});

  call(Function action) {
    _timer?.cancel();
    _timer = Timer(delay, action);
  }
}

final _debouncer = Debouncer();

_debouncer(() {
     // your action
})

I prefer having the delay explicitly passed in each time so the delay is obvious.

But pretty cool, didn't know about the call function!

Another slight variation - it can also be convenient to return a function from the call method for the purpose of allowing us to pass arguments to the callback. For example, when listening to input coming through a stream, we can just do someStream.stream.listen(Debounce(Duration(milliseconds: 350), _fnThatTakesArgs)() with the following:

class Debounce {
  final Duration delay;
  Timer _timer;

  Debounce(this.delay);

  Function call(Function callback) {
    return (args) {
      _timer?.cancel();
      _timer = Timer(delay, () => callback(args));
    };
  }
}

How will you dispose of the timer?

@SAGARSURI, you can have something like this and call its dispose function from your user class.

class Debouncer {
  Debouncer({this.delay = const Duration(milliseconds: 300)});

  final Duration delay;
  Timer? _timer;

  void call(void Function() callback) {
    _timer?.cancel();
    _timer = Timer(delay, callback);
  }

  void dispose() {
    _timer?.cancel(); // You can comment-out this line if you want. I am not sure if this call brings any value.
    _timer = null;
  }
}