emitter.prependOnceListener(eventName, listener)

    将名为 eventName 的事件的单次 listener 函数添加到监听器数组的开头。 下次触发 eventName 时,将移除此监听器,然后再调用。

    Adds a one-time listener function for the event named eventName to the beginning of the listeners array. The next time eventName is triggered, this listener is removed, and then invoked.

    server.prependOnceListener('connection', (stream) => {
      console.log('Ah, we have our first user!');

    Returns a reference to the EventEmitter, so that calls can be chained.