delay method

Future delay([ FutureOr callback()? ])

Delays the execution of a callback or code block by the specified number of seconds.

The callback parameter is an optional function that will be executed after the specified delay. If provided, it will be called asynchronously once the delay has completed.

Example:

void main() async {
  print('+ wait for 2 seconds');
  await 2.delay();
  print('- 2 seconds completed');
  print('+ callback in 1.2sec');
  1.delay(() => print('- 1.2sec callback called'));
  print('currently running callback 1.2sec');
}

The above example waits for 2 seconds before printing '- 2 seconds completed'. It then waits for an additional 1.2 seconds before executing the callback that prints '- 1.2sec callback called'. Finally, it prints 'currently running callback 1.2sec'.

Implementation

Future delay([FutureOr Function()? callback]) async {
  final completer = Completer<void>();
  Timer(Duration(milliseconds: (this * 1000).round()), () {
    if (!completer.isCompleted) {
      completer.complete();
      callback?.call();
    }
  });
  return completer.future;
}