this.data is always coming has ‘undefined’ file save in Angular

Question

/*fileName = '';*/
  fileSelected = false;
  invalidFileType = false;
  file: File = null; // Variable to store file
  data: any;
  jsonData: any;
  displayError: boolean;
  errorText: string;
  responseData: any;

  @ViewChild('fileUpload') fileUpload: ElementRef;
  /*fileName = '';*/
  fileSelected = false;
  invalidFileType = false;
  file: File = null; // Variable to store file
  data: any;
  jsonData: any;
  displayError: boolean;
  errorText: string;
  responseData: any;

  @ViewChild('fileUpload') fileUpload: ElementRef;

  Reset(form) {
    this.fileUpload.nativeElement.value = "";
    console.log("Reset completed");
  }

  UploadFile(filevalue) {

    const reqbody = {
      filename: this.file.name,
      lines: JSON.stringify(this.data)
    };

    var route = "FileSave";
    this.dataService.post(reqbody, route).subscribe(
      (data: any[]) => {
        console.log("Response data: " + data);
        LoggerService.success(`File successfully uploaded to server`, true, false);
        this.responseData = data;
      },
      (error: Response) => {
        this.displayError = true;
        this.errorText = `Error saving API service ${error.status}`;
      });
  }

  onFileChange(event: any): void {
    this.file = event.target.files[0];

         this.fileSelected = true;
        this.invalidFileType = false;
        this.readFile();

  }

  readFile(): void {

    fileReader.onload = (e: any) => {
      const binaryString = e.target.result;
      console.log(binaryString);
      const workBook = XLSX.read(binaryString, { type: 'binary' });

      const workSheetName = workBook.SheetNames[0];
      const workSheet = workBook.Sheets[workSheetName];

      // Parse the Excel data into JSON format
      this.data = XLSX.utils.sheet_to_json(workSheet);
      console.log(this.data);
    }
  }
}

hkh