我有下面的类FileInfo，它实现了IFileInfo接口。该类定义了一个实例成员函数ext和一个函数getExt（）。在我的组件中，我有一个名为openTempFolder（）的私有方法，它基本上是一个超文本传输协议调用，返回一个FileInfo数组。我一直得到一个TypeError，即getExt（）不是一个函数，并且ext在调用它们时一直返回未定义。我在这里做错了什么？

我正在发布相关代码，

export class FileInfo implements IFileInfo {
  constructor(
    public exists: boolean,
    public length: number,
    public physicalPath: string,
    public name: string,
    public lastModified: Date,
    public isDirectory: boolean,
    public ext: () => string,
  ) {
    this.exists = exists;
    this.length = length;
    this.physicalPath = physicalPath;
    this.name = name;
    this.lastModified = lastModified;
    this.isDirectory = isDirectory;
    this.ext = () => {
      return this.name.replace(/^.*\./, '');
    };
  }
  getExt() {
    return this.name.replace(/^.*\./, '');
  }
}

在我的组件中，我这样称呼，

export class FileManagerComponent implements OnInit, OnDestroy {
  @ViewChild('fileManager') public fileManager;
  public contents: Array<FileInfo> = new Array<FileInfo>();
  private unsubscribe: Subject<void> = new Subject();

....

 private openTempFolder() {
    this.httpService
      .getRequest<Array<FileInfo>>('FileManager/OpenTemporaryDirectory/Uploads')
      .subscribe((r: HttpResponse<Array<FileInfo>>) => {
        this.contents = r.body;
        this.contents.forEach(e => {
          console.log(e.getExt()); // TypeError
          console.log(e.ext()); // Undefined
        });
      });
  }
}