Code: Select all
const workbook = new ExcelJS.Workbook();
await workbook.xlsx.load(buffer);
const targetSheet = workbook.worksheets[1];
let row = targetSheet.getRow(rowNumber); // Target row
cell = row.getCell(4); // Target cell
cell.dataValidation = {
type: 'list',
allowBlank: false,
formulae: ['"Option1,Option2,Option3"']
};