arrayToCSV

Converts a 2D array to a comma-separated values (CSV) string.

• Use Array.prototype.map() and Array.prototype.join(delimiter) to combine individual 1D arrays (rows) into strings.
• Use Array.prototype.join('\n') to combine all rows into a CSV string, separating each row with a newline.
• Omit the second argument, delimiter, to use a default delimiter of ,.

const arrayToCSV = (arr, delimiter = ',') =>
  arr
    .map(v =>
      v.map(x => (isNaN(x) ? `"${x.replace(/"/g, '""')}"` : x)).join(delimiter)
    )
    .join('\n');

arrayToCSV([['a', 'b'], ['c', 'd']]); // '"a","b"\n"c","d"'
arrayToCSV([['a', 'b'], ['c', 'd']], ';'); // '"a";"b"\n"c";"d"'
arrayToCSV([['a', '"b" great'], ['c', 3.1415]]);
// '"a","""b"" great"\n"c",3.1415'