title: add row before header excel js in angular
body: <p>i'm exporting json to excel by using excel js. json is getting sucessfully exported to sheet .but now i want to add one row which describes details of <strong>sheet above the header text</strong>.</p>
  <p>for more details please refer <a href="https://i.stack.imgur.com/eI5Ou.png" rel="nofollow noreferrer">image</a></p>
  <p>code as follows</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>import { Injectable } from '@angular/core';
  import * as FileSaver from 'file-saver';
  import * as XLSX from 'xlsx';
  
  const EXCEL_TYPE = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=UTF-8';
  const EXCEL_EXTENSION = '.xlsx';
  import { DatePipe } from '@angular/common';
  import { Workbook } from 'exceljs';
  
  @Injectable()
  export class ExcelService {
  
    constructor( private datePipe :  DatePipe) { }
  
    public exportAsExcelFile(json: any[], excelFileName: string): void {
      const title = 'Absent Report';
      const worksheet: XLSX.WorkSheet = XLSX.utils.json_to_sheet(json);
     
      console.log('worksheet',worksheet);
      const workbook: XLSX.WorkBook = { Sheets: { 'data': worksheet }, SheetNames: ['data'] };
      const excelBuffer: any = XLSX.write(workbook, { bookType: 'xlsx', type: 'array' });
      //const excelBuffer: any = XLSX.write(workbook, { bookType: 'xlsx', type: 'buffer' });
      this.saveAsExcelFile(excelBuffer, excelFileName);
  
      let titleRow = worksheet.addRow(title);
      titleRow.font = { name: 'Comic Sans MS', family: 4, size: 16, underline: 'double', bold: true }
      worksheet.addRow([titleRow]);
   
      // let subTitleRow = worksheet.addRow(['Date : ' + this.datePipe.transform(new Date(), 'medium')])
  
    }
  
    private saveAsExcelFile(buffer: any, fileName: string): void {
      const data: Blob = new Blob([buffer], {
        type: EXCEL_TYPE
      });
      FileSaver.saveAs(data, fileName + this.datePipe.transform(new Date(),"ddMMyyyy hh:mm") + EXCEL_EXTENSION);
    }
  
  }</code></pre>
  </div>
  </div>
  </p>