How to change 9 digit uploaded data into 10-digit number in Angular

Hi Team,

I am totally new to angular. I have angular UI where we upload a .CSV file with 6 columns and their respective data, so before I invoke .net API, I need to change. If the 1st column has data with 9 digits, then we need to change it to 10 digits just by prefixing ‘0’; for example, If the Excel 1st (AccountNumber)column data is ‘217614234’, this number has to be changed to ‘0217614234’, after the changed entire file content I need pass to API.

Here is my working Code for uploaded data that is being passed to API. Now, I need to add a condition to change the number to 10 digits. If I found a 9-digit number, this is applicable only to the 1st (AccountNumber) column in the .csv file that was uploaded.

Here is a sample exelsheet - https://i.stack.imgur.com/mynhP.png

<input #fileUpload type="file" class="file-upload" name="fileUpload" id="fileUpload" accept=".xlsx,.xls,.csv" required (change)="onFileChange($event)">
<button (click)="UploadFile(form.value)" type="button" mat-raised-button color="primary" [disabled]="!fileSelected">Upload</button>

onFileChange(event: any): void {
  this.file = event.target.files[0];
  if (this.file) {
    console.log("this.file.type: " + this.file.type);
    const fileName = this.file.name;
    this.fileSelected = true;
    this.invalidFileType = false;
    this.invalidFileSize = false;
    this.invalidFileRecords = false;
    let file: File = this.file;
    var value;
    const fileReader = new FileReader();
    fileReader.onload = (e: any) => {
      value = e.target.result;
      this.data = value;
      var rows = e.target.result.split("\n");
      if (rows.length > 6003) {
        LoggerService.error(`upload records less than 6K.`, true, true);
      }
    };
    fileReader.readAsBinaryString(this.file);
  }
}

UploadFile(filevalue) {
  const reqbody = {
    filename: this.file?.name,
    destinationPath: '',
    lines: this.data.replace(/[^a-zA-Z0-9,\n\r.'" ]/g, "").split('\r\n')
  };
  var route = "CallNETAPI";
  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 from CallNETAPI API service ${error.status}`;
    }
  );
}