返回名为 eventName 的事件的监听器数组的副本,包括任何封装器(例如由 .once() 创建的封装器)。

    Returns a copy of the array of listeners for the event named eventName, including any wrappers (such as those created by .once()).

    const emitter = new EventEmitter();
    emitter.once('log', () => console.log('log once'));
    // Returns a new Array with a function `onceWrapper` which has a property
    // `listener` which contains the original listener bound above
    const listeners = emitter.rawListeners('log');
    const logFnWrapper = listeners[0];
    // Logs "log once" to the console and does not unbind the `once` event
    // Logs "log once" to the console and removes the listener
    emitter.on('log', () => console.log('log persistently'));
    // Will return a new Array with a single function bound by `.on()` above
    const newListeners = emitter.rawListeners('log');
    // Logs "log persistently" twice