如何使用Vanilla Javascript向本地系统中的Excel文件添加新列？

<input type="file" id="excelFile" accept=".xlsx, .xls" />

<script src="https://unpkg.com/xlsx/dist/xlsx.full.min.js"></script>

document.getElementById('excelFile').addEventListener('change', handleFile, false);

function handleFile(e) {
  var files = e.target.files;
  var file = files[0];
  
  var reader = new FileReader();
  reader.onload = function(e) {
    var data = new Uint8Array(e.target.result);
    var workbook = XLSX.read(data, {type: 'array'});
    
    // 在这里进行Excel文件的操作，添加新列等
  };
  reader.readAsArrayBuffer(file);
}

var worksheet = workbook.Sheets[workbook.SheetNames[0]];
var jsonData = XLSX.utils.sheet_to_json(worksheet, {header: 1});

// 添加新列
var newColumn = ['New Column'];
jsonData[0] = jsonData[0].concat(newColumn);

// 将修改后的数据保存回Excel文件
var newWorksheet = XLSX.utils.aoa_to_sheet(jsonData);
workbook.Sheets[workbook.SheetNames[0]] = newWorksheet;
var newWorkbook = XLSX.utils.book_new();
XLSX.utils.book_append_sheet(newWorkbook, newWorksheet, workbook.SheetNames[0]);

// 保存Excel文件
var excelBuffer = XLSX.write(newWorkbook, {type: 'array', bookType: 'xlsx'});
saveAs(new Blob([excelBuffer], {type: 'application/octet-stream'}), 'newFile.xlsx');

<script src="https://unpkg.com/file-saver/dist/FileSaver.min.js"></script>