Minimal function to save a CSV from memory in browser JavaScript. Consider this code as public domain, since it's trivial.

downloadCSV.ts

export function escapeCSV(value: string): string {
  if (/^[-+._=\/a-z0-9]*$/i.test(value)) {
    return value;
  }

  return `"${value.replace(/"/g, '""')}"`;
}

export function buildCSV(data: string[][]): string {
  const buf: string[] = ['\ufeff'];  // BOM
  for (const row of data) {
    if (row.length > 0) {
      buf.push(escapeCSV(row[0]));

      for (let index = 1; index < row.length; ++ index) {
        buf.push(',', escapeCSV(row[index]));
      }
    }
    buf.push('\r\n');
  }
  return buf.join('');
}

export function downloadCSV(filename: string, data: string[][]): void {
  const blob = new Blob([buildCSV(data)], { type: 'text/csv' });
  const url = URL.createObjectURL(blob);
  const link = document.createElement('a');

  link.download = filename;
  link.href = url;
  link.style.opacity = '0';
  link.style.position = 'fixed';
  link.style.right = '0';
  link.style.bottom = '0';

  document.body.appendChild(link);
  link.click();

  setTimeout(() => {
    URL.revokeObjectURL(url);
    link.parentNode?.removeChild(link);
  }, 0);
}