isBlank function

Checks whether a text is missing or holds only whitespace: a required field left empty.

import { isBlank } from 'utils';

Signature

export function isBlank(input: string | null | undefined): boolean

Parameters

Name	Description
input	A string, null or undefined.

Returns

true for null, undefined, '' or whitespace only.

Example

isBlank('  \n'); // true
isBlank(' a '); // false

Tests

Line coverage: 100 %.

• ✅ checks null as true
• ✅ checks undefined as true
• ✅ checks "" as true
• ✅ checks " \n\t" as true
• ✅ checks " a " as false
• ✅ checks "0" as false

Source

src/string/is-blank.ts (on GitHub)

Source code

/**
 * Checks whether a text is missing or holds only whitespace: a required field left empty.
 *
 * @param input - A string, `null` or `undefined`.
 * @returns `true` for `null`, `undefined`, `''` or whitespace only.
 * @example
 * isBlank('  \n'); // true
 * isBlank(' a '); // false
 */
export function isBlank(input: string | null | undefined): boolean {
  return input === null || input === undefined || input.trim() === '';
}

Test file

import { isBlank } from './is-blank';

describe(isBlank, () => {
  it.for([
    [null, true],
    [undefined, true],
    ['', true],
    [' \n\t', true],
    [' a ', false],
    ['0', false],
  ] as const)('checks %j as %s', ([input, expected]) => {
    expect(isBlank(input)).toBe(expected);
  });
});

Keywords: is, blank, strings, function