padString

1/**
2 * Pads a string on both sides to reach the desired total length.
3 * If the target length is less than or equal to the original string length,
4 * the original string is returned unchanged.
5 *
6 * @param str - The string to pad.
7 * @param length - The desired total length of the final string.
8 * @param padChar - The character to use for padding (default is a space).
9 * @returns The padded string.
10 */
11export function padString(str: string, length: number, padChar: string = ' '): string {
12  const totalPadding = Math.max(length - str.length, 0);
13  const left = Math.floor(totalPadding / 2);
14  const right = totalPadding - left;
15  return padChar.repeat(left) + str + padChar.repeat(right);
16}

1test('padString - pads evenly on both sides', () => {
2  expect(padString('abc', 7)).toBe('  abc  ');
3});
4
5test('padString - pads with custom character', () => {
6  expect(padString('abc', 8, '-')).toBe('--abc---');
7});
8
9test('padString - string already meets or exceeds length', () => {
10  expect(padString('hello world', 5)).toBe('hello world');
11});
12
13test('padString - exact match to length', () => {
14  expect(padString('test', 4)).toBe('test');
15});
16
17test('padString - pads with odd total padding', () => {
18  expect(padString('abc', 6, '.')).toBe('.abc..');
19});
20
21test('padString - pads empty string', () => {
22  expect(padString('', 4, '*')).toBe('****');
23});