EventEmitter

Bling 使用了 eventemitter3，你可以通过 Bling.EventEmitter 获得，举个栗子：

const EE = new Bling.EventEmitter();
EE.on('event', () => {
  console.log('an event occurred!');
});
EE.emit('event');
//=> an event occurred!

实例化的 EE 对象方法如下：

on(event, fn, context)                      // Add a listener for a given event.
off(event, fn, context, once)               // Remove the listeners of a given event.
once(event, fn, context)                    // Add a one-time listener for a given event.
emit(event, a1, a2, a3, a4, a5)             // Calls each of the listeners registered for a given event.
addListener(t,e,n)                          // Alias of method 'on'
removeListener(event, fn, context, once)    // Alias of method 'off'
listeners(event, exists)                    // Return the listeners registered for a given event.
removeAllListeners(event)                   // Remove all listeners, or those of the specified event.
eventNames()                                // Return an array listing the events for which the emitter has registered listeners.