on static method

Future<void> on(
  1. String eventName,
  2. Function callback
)

Implementation

static Future<void> on(String eventName, Function callback) async {
  if (callbacks.containsKey(eventName)) {
    var existed = callbacks[eventName];
    existed?.add(callback);
    callbacks.update(eventName, (val) => existed);
  } else {
    callbacks.putIfAbsent(eventName, () => List.of([callback]));
  }
  _libraryEventSubscription.resume();
}