Creating excel file and writing to it with ExcelJS

Question

I wrote a script that creates a new excel file with ExcelJS. Adds 3 headers and inserts 2 rows. Then saves that file to disk.

In the next step it should read that previously saved file, add 1 row and save it again under a new name. I can't find the reason why the second part where I try to add 3rd row never happens. Both files look the same and there are no errors in console.

const Excel = require('exceljs');

async function exTest(){
  const workbook = new Excel.Workbook();
  const worksheet = workbook.addWorksheet("My Sheet");

worksheet.columns = [
  {header: 'Id', key: 'id', width: 10},
  {header: 'Name', key: 'name', width: 32}, 
  {header: 'D.O.B.', key: 'dob', width: 15,}
];

worksheet.addRow({id: 1, name: 'John Doe', dob: new Date(1970, 1, 1)});
worksheet.addRow({id: 2, name: 'Jane Doe', dob: new Date(1965, 1, 7)});

// save under export.xlsx
await workbook.xlsx.writeFile('export.xlsx');

// load a copy of export.xlsx
const newWorkbook = new Excel.Workbook();
await newWorkbook.xlsx.readFile('export.xlsx');

const newworksheet = newWorkbook.getWorksheet('My Sheet');
newworksheet.addRow(
  {id: 3, name: 'New Guy', dob: new Date(2000, 1, 1)}
);

await newWorkbook.xlsx.writeFile('export2.xlsx');

console.log("File is written");
};

exTest();

Answer 1

Solved it by adding array to describe columns in second part of the code. Then the 3rd row was added successfully. When passing an object with column names to addRow() I had to provide a description of columns that already existed in excel file.

const Excel = require('exceljs');

async function exTest(){
  const workbook = new Excel.Workbook();
  const worksheet = workbook.addWorksheet("My Sheet");

worksheet.columns = [
 {header: 'Id', key: 'id', width: 10},
 {header: 'Name', key: 'name', width: 32}, 
 {header: 'D.O.B.', key: 'dob', width: 15,}
];

worksheet.addRow({id: 1, name: 'John Doe', dob: new Date(1970, 1, 1)});
worksheet.addRow({id: 2, name: 'Jane Doe', dob: new Date(1965, 1, 7)});

// save under export.xlsx
await workbook.xlsx.writeFile('export.xlsx');

//load a copy of export.xlsx
const newWorkbook = new Excel.Workbook();
await newWorkbook.xlsx.readFile('export.xlsx');

const newworksheet = newWorkbook.getWorksheet('My Sheet');
newworksheet.columns = [
 {header: 'Id', key: 'id', width: 10},
 {header: 'Name', key: 'name', width: 32}, 
 {header: 'D.O.B.', key: 'dob', width: 15,}
];
await newworksheet.addRow({id: 3, name: 'New Guy', dob: new Date(2000, 1, 1)});

await newWorkbook.xlsx.writeFile('export2.xlsx');

console.log("File is written");

};

exTest();