获取TypeError'回调'不是事件发射器上的函数

Question

我试图让这个模块在Node 8.7上运行 当我运行它时，控制台抛出类型错误回调不是一个函数（在emit方法上）。

我正在将这个模块与一个类一起使用，以使另一个类继承自Event Emitter。

当我在一个文件上尝试相同的代码（使用Event Emitter，另一个类作为单独的类）时，Node会不断地抛出随机错误。

//export class EventEmitter...

class EventEmitter{
    constructor(){
        this.events = {};
    }
    on(eventName,callback){
        if (typeof this.events[eventName] !== 'object') {
            this.events[eventName] = [];
        }

        this.events[eventName].push(callback);
    }
    emit(eventName, ...rest) {
        if (this.events[eventName]) {
          this.events[eventName].forEach((callback) => {
            callback(rest);
          });
        } else {
          console.log("The event doesn't exists.");
        }
      }

    off(eventName,callback){
        var index;

            if (typeof this.events[eventName] === 'object') {
                index = this.events[eventName].indexOf(callback);

                if (index > -1) {
                    this.events[eventName].splice(index, 1);
                }
            }
    }
}

module.exports = EventEmitter;

按要求添加了movie.js类和对象

//import {EventEmitter} from "./eventEmitter.js"
var EventEmitter = require("./eventEmitter.js");

class Movie extends EventEmitter {

        constructor(name,year,duration){
            super();//invokes father class constructor
            this.title = name;
            this.year = year;
            this.duration = duration;
            this.startPlay = 0;
            this.currentMovieTime = 0;//aca iba var date
        }
        play(){
            var date = new Date();//agregada nueva
            this.startPlay = date.getMinutes();
        }
        pause(){
            var date = new Date(); //agregada nueva
            let time2 = date.getMinutes();
            this.currentMovieTime+= (time2 - this.startPlay);
            this.startPlay = time2;
            if(this.currentMovieTime > this.duration)
                this.currentMovieTime = this.duration;
        }
        resume(){
            this.startPlay =0;
            this.currentMovieTime=0;
        }
    }

    let film = new Movie("Harry Potter",2001,120);
    let playFunc = film.play();
    film.on('play',playFunc);
    let resumeFunc = film.resume();
    film.on('resume',resumeFunc);
    let pauseFunc = film.pause();
    film.on('pause',pauseFunc);

    film.emit('play');
    film.emit('pause');
    film.emit('resume');