使用play（）方法后报错Cannot read property 'play' of undefined。

@ViewChild('audio', { static: true }) private audio: ElementRef;
private audioEl: HTMLAudioElement;

 onCanplay(){
this.play();

}

play(){
this.audioEl.play();
}

报错Cannot read property 'play' of undefined。

https://blog.csdn.net/zzwwjjdj1/article/details/52125717