pluralize function

Picks the singular or plural form of a word for a count. French takes the singular for 0 too: pass Math.abs(count) < 2 as isSingular.

import { pluralize } from 'utils';

Signature

export function pluralize(
  count: number,
  singular: string,
  plural = `${singular}s`,
  isSingular = Math.abs(count) === 1,
): string

Parameters

Name	Description
count	The number of items.
singular	The singular form, such as 'alarm'.
plural	The plural form. Defaults to singular followed by s.
isSingular	Whether the count takes the singular. Defaults to Math.abs(count) === 1 (English).

Returns

The form matching the count.

Example

pluralize(3, 'alarm'); // 'alarms'
pluralize(0, 'alarme', 'alarmes', Math.abs(0) < 2); // 'alarme'

Tests

Line coverage: 100 %.

• ✅ picks the form for 1
• ✅ picks the form for -1
• ✅ picks the form for 0
• ✅ picks the form for 3
• ✅ picks the form for 1.5
• ✅ uses the given plural and singular rule
• ✅ takes the defaults

Source

src/string/pluralize.ts (on GitHub)

Source code

/**
 * Picks the singular or plural form of a word for a count. French takes the singular for 0 too: pass
 * `Math.abs(count) < 2` as `isSingular`.
 *
 * @param count - The number of items.
 * @param singular - The singular form, such as `'alarm'`.
 * @param plural - The plural form. Defaults to `singular` followed by `s`.
 * @param isSingular - Whether the count takes the singular. Defaults to `Math.abs(count) === 1` (English).
 * @returns The form matching the count.
 * @example
 * pluralize(3, 'alarm'); // 'alarms'
 * pluralize(0, 'alarme', 'alarmes', Math.abs(0) < 2); // 'alarme'
 */
export function pluralize(
  count: number,
  singular: string,
  plural = `${singular}s`,
  isSingular = Math.abs(count) === 1,
): string {
  return isSingular ? singular : plural;
}

Test file

import { pluralize } from './pluralize';

describe(pluralize, () => {
  it.for([
    [1, 'alarm'],
    [-1, 'alarm'],
    [0, 'alarms'],
    [3, 'alarms'],
    [1.5, 'alarms'],
  ] as const)('picks the form for %s', ([count, expected]) => {
    expect(pluralize(count, 'alarm', 'alarms', Math.abs(count) === 1)).toBe(expected);
  });

  it('uses the given plural and singular rule', () => {
    expect(pluralize(2, 'box', 'boxes', Math.abs(2) === 1)).toBe('boxes');
    expect(pluralize(0, 'alarme', 'alarmes', true)).toBe('alarme');
  });

  it('takes the defaults', () => {
    expect(pluralize(3, 'alarm')).toStrictEqual(pluralize(3, 'alarm', 'alarms', false));
  });
});

Keywords: pluralize, strings, function