angular - 将 Youtube API 与 Angular 6 (Typescript) 结合使用

Question

我能够让 Youtube Iframe API(以某种方式)在我的 Angular 6 应用程序中运行。但是，我想从我控制的列表中为它提供动态 videoIds。我的计划是收听来自播放器的事件，然后在播放完当前视频后加载另一个视频。但我似乎无法解决这个问题。我仍在学习 Typescript 和 Angular，我很好奇为什么我从 IFrame API 播放器中调用的任何函数调用的任何方法都会出现 Uncaught TypeError:

这是我的代码:

import { Component, OnInit, AfterViewInit } from '@angular/core';
import { Video } from '../shared/model/video.model';
import { Subscription } from 'rxjs';
import { VideoPlayerService } from '../shared/services/video-player.service';

@Component({
  selector: 'ntv-video-player',
  templateUrl: './video-player.component.html',
  styleUrls: ['./video-player.component.css']
})
export class VideoPlayerComponent implements OnInit, AfterViewInit {

  player;
  video: Video;
  videos: Video[];
  videoSubscription: Subscription;

  constructor(private videoService: VideoPlayerService) { }

  ngAfterViewInit() {
    const doc = (<any>window).document;
    const playerApiScript = doc.createElement('script');
    playerApiScript.type = 'text/javascript';
    playerApiScript.src = 'https://www.youtube.com/iframe_api';
    doc.body.appendChild(playerApiScript);
  }

  ngOnInit() {

    (<any>window).onYouTubeIframeAPIReady = () => {
      this.player = new (<any>window).YT.Player('player', {
        height: '100%',
        width: '100%',
        // videoId: this.getVideo(),
        events: {
          'onReady': this.onPlayerReady,
          'onStateChange': this.onPlayerStateChange
        },
        playerVars: {
          autoplay: 1,
          controls: 0,
          modestbranding: 1,
          // playlist: 'UG3sfZKtCQI,ALZHF5UqnU4,x9ZkC3OgI78',
          rel: 0,
          showInfo: 0
        }
      });
    };
  }



  // The API calls this function when the player's state changes.
  onPlayerStateChange(event) {
    console.log('onPlayerStateChange');
    console.log(event.data);
  }

  // The API will call this function when the video player is ready
  onPlayerReady(event) {
    console.log(event);

    const videoId = this.getVideo();
    event.target.cueVideoById({
      'videoId': videoId
    });
    event.target.playVideo();
  }

  getVideo() {
    return '60ItHLz5WEA';
  }

}

这是我遇到的错误:

    Uncaught TypeError: Cannot read property 'getVideo' of undefined
    at push../src/app/video-player/video-player.component.ts.VideoPlayerComponent.onPlayerReady (video-player.component.ts:63)
    at M.h.G (www-widgetapi.js:48)
    at Y.h.o (www-widgetapi.js:92)
    at Y.h.H (www-widgetapi.js:105)
    at Wa.g (www-widgetapi.js:81)
    at Oa.f (www-widgetapi.js:70)
    at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:421)
    at Zone.push../node_modules/zone.js/dist/zone.js.Zone.runTask (zone.js:188)
    at ZoneTask.push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask [as invoke] (zone.js:496)
    at invokeTask (zone.js:1540)
push../src/app/video-player/video-player.component.ts.VideoPlayerComponent.onPlayerReady    @   video-player.component.ts:63
h.G @   www-widgetapi.js:48
h.o @   www-widgetapi.js:92
h.H @   www-widgetapi.js:105
Wa.g    @   www-widgetapi.js:81
Oa.f    @   www-widgetapi.js:70
push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask    @   zone.js:421
push../node_modules/zone.js/dist/zone.js.Zone.runTask   @   zone.js:188
push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask    @   zone.js:496
invokeTask  @   zone.js:1540
globalZoneAwareCallback

如果我从“videoId”属性调用 this.getVideo() 似乎可以正常工作，但我希望能够调用它 onPlayerReady 或 onPlayerStateChange 以便使其更具动态性。以前有人做过吗？ Angular 的文档不多。

提前致谢。

Answer 1

我认为您遇到的是范围问题，您的 OnPlayerReady 函数未在您的类范围内执行，而是在 youtube 播放器的范围内执行。我是从错误消息“无法读取未定义的属性‘getVideo’”中推断出来的。在这个执行点，“this”并不是它看起来的样子。

尝试像这样更改您的事件分配代码:

 events: {
          'onReady': (event) => { this.onPlayerReady(event); },
          'onStateChange': (event) => { this.onPlayerStateChange(event); }
        },