on method

void on(
  1. dynamic eventName,
  2. EventCallback f, {
  3. String eventReceive = '',
})

eventName通知名称，eventReceive接收者名称（区分不同位置的监听，方便单个监听移除）

Implementation

void on(eventName, EventCallback f, {String eventReceive = ''}) {
  _eMap[eventName] ??= {
    eventReceive: <EventCallback>[],
  };
  _eMap[eventName]![eventReceive] ??= <EventCallback>[];
  _eMap[eventName]![eventReceive]?.add(f);
}