This function takes an array of arrays as input and returns a CSV string. The first element of the input array is assumed to be the header row.

ConvertArrayToCSV.js

function convertArrayToCSV(arr) {
  const arrayCopy = [...arr];
  const header = arrayCopy.shift();
  const csv = [
    header.join(','),
    ...arrayCopy.map((row) => row.join(',')),
  ].join('\n');
  return csv;
}

const data = [
  ['Name', 'Age', 'City'],
  ['John', '25', 'New York'],
  ['Jane', '30', 'Los Angeles'],
  ['Bob', '40', 'San Francisco'],
];

const csv = convertArrayToCSV(data);
console.log(csv);