toSafeFilename

1/**
2 * Converts a string to a safe filename by removing or replacing invalid characters.
3 *
4 * @param name - The input string to convert.
5 * @param replacement - The character to replace invalid characters with (default: "_").
6 * @returns A sanitized string safe to use as a filename.
7 */
8export function toSafeFilename(name: string, replacement = '_'): string {
9  return name
10    .trim()
11    .replace(/[<>:"/\\|?*\x00-\x1F]/g, replacement) // Windows reserved characters
12    .replace(/[\u{0080}-\u{FFFF}]/gu, replacement)   // Control and unicode chars
13    .replace(/[\s.]+$/g, '')                         // Remove trailing spaces or dots
14    .substring(0, 255);                              // Limit length for most filesystems
15}

1test('toSafeFilename - replaces unsafe characters', () => {
2  expect(toSafeFilename('report:2023/12/31')).toBe('report_2023_12_31');
3});
4
5test('toSafeFilename - trims trailing dots and spaces', () => {
6  expect(toSafeFilename('file name. ')).toBe('file name');
7});
8
9test('toSafeFilename - handles unicode and control chars', () => {
10  expect(toSafeFilename('emoji💥test\x00file')).toBe('emoji_test_file');
11});
12
13test('toSafeFilename - uses custom replacement', () => {
14  expect(toSafeFilename('path/to\\file', '-')).toBe('path-to-file');
15});
16
17test('toSafeFilename - truncates very long filenames', () => {
18  const long = 'a'.repeat(300);
19  expect(toSafeFilename(long).length).toBeLessThanOrEqual(255);
20});