尝试访问数组时未定义

Question

我在typescript中有一个服务类，在该类中我声明了一个公共字符串数组，但是当我尝试将其推入数组时，它将引发未定义的异常。我在这里怎么可能做错了？

  

无法读取未定义的属性'audioInput'

该类的源代码是：

export class AudioService {
    public audioInput:Array<String>=[];
    _navigator=<any> navigator;
    constructor(){
    }
    getDevices(){
        this._navigator.mediaDevices.enumerateDevices().then(this.gotDevices)
    }
    gotDevices(deviceInfos) : any {
      for (let i = 0; i !== deviceInfos.length; ++i) {
        const deviceInfo = deviceInfos[i];
        let value = deviceInfo.deviceId;
        if (deviceInfo.kind === 'audioinput') {
          this.audioInput.push(deviceInfo.label);
        }
      }
    }
}

Answer 1

如果您要在Cordova中访问“ this”。它指的是窗口对象。您需要定义让我= this;

export class AudioService {
    public audioInput:Array<String>=[];
    _navigator=<any> navigator;
    constructor(){
    }
    getDevices(){
        this._navigator.mediaDevices.enumerateDevices().then(this.gotDevices)
    }
    gotDevices(deviceInfos) : any {
      let me = this.
      for (let i = 0; i !== deviceInfos.length; ++i) {
        const deviceInfo = deviceInfos[i];
        let value = deviceInfo.deviceId;
        if (deviceInfo.kind === 'audioinput') {
          me.audioInput.push(deviceInfo.label);
        }
      }
    }
}