function isWhitespace<S extends string>(
  it: S,
): it is IsWhitespace<S, S, string extends S ? WhitespaceString<S> : never>;

Checks if the provided value is either a string or an iterable of strings that consists entirely of whitespace characters.

This function is useful for validating input data, ensuring that it contains characters other than whitespace.

true if the value is a string or an iterable of strings that consists entirely of whitespace characters, false otherwise.

Strings

whitespace

import { isWhitespace } from "jsr:@nick/is/whitespace";

console.log(isWhitespace("   ")); // true
console.log(isWhitespace("abc")); // false
console.log(isWhitespace("  a ")); // false
console.log(isWhitespace("")); // false
console.log(isWhitespace(" \n\t ")); // true

function isWhitespace(it: unknown): it is WhitespaceString;

function isWhitespace(it: unknown): it is WhitespaceString;

function isWhitespaceChar(it: unknown): it is Whitespace;

Checks if a given character is a whitespace character.

This function checks if the provided character is one of the recognized whitespace characters, including spaces, tabs, newlines, and additional Unicode whitespace characters.

true if the character is a whitespace character, false otherwise.

Strings

whitespace

import { isWhitespaceChar } from "jsr:@nick/is/whitespace";

console.log(isWhitespaceChar(" ")); // true
console.log(isWhitespaceChar("\n")); // true
console.log(isWhitespaceChar("\t")); // true
console.log(isWhitespaceChar("a")); // false

function isWhitespaceCode(it: unknown): it is WhitespaceCode;

Checks if a given value is a whitespace character code.

This function checks if the provided value is a number and if it is included in the list of recognized whitespace character codes, which is exposed as the WHITESPACE\_CODES array.

true if the value is a whitespace character code, false otherwise.

function isWhitespaceLike<S extends string>(
  it: S,
): it is IsWhitespace<S, S, never>;

Checks if the provided value is either a string or an iterable of strings that consists entirely of whitespace characters.

This function is useful for validating input data, ensuring that it contains characters other than whitespace.

true if the value is a string or an iterable of strings that consists entirely of whitespace characters, false otherwise.

function isWhitespaceLike<N extends number>(
  it: N,
): it is IsWhitespaceCode<N, N, never>;

Checks if the provided value is a whitespace character code.

This function checks if the provided value is a number and if it is included in the list of recognized whitespace character codes, which is exposed as the WHITESPACE\_CODES array.

true if the value is a whitespace character code, false otherwise.

function isWhitespaceLike(it: Iterable<string>): it is Iterable<Whitespace>;

Checks if the provided value is either a string or an iterable of strings that consists entirely of whitespace characters.

This function is useful for validating input data, ensuring that it contains characters other than whitespace.

true if the value is a string or an iterable of strings that consists entirely of whitespace characters, false otherwise.

function isWhitespaceLike(it: number): it is WhitespaceCode;

Checks if the provided value is a whitespace character code.

true if the value is a whitespace character code, false otherwise.

function isWhitespaceLike(it: unknown): it is WhitespaceLike;

function isWhitespaceLike(
  it: unknown,
): it is string | WhitespaceCode | Iterable<Whitespace>;

export type IsWhitespace<T extends string, True = true, False = false> =
  IsNever<T> extends true ? False
    : IsAny<T> extends true ? True
    : T extends Whitespace ? True
    : T extends `${Whitespace}${infer R}` ? IsWhitespace<R, True, False>
    : False;

If the given string T is whitespace, this type will resolve to the True type parameter (default: true). Otherwise, it will resolve to the False type parameter (default: false).

• T extends string
• True (default: true)
• False (default: false)

Types

whitespace

export type IsWhitespaceChar<T extends string, True = true, False = false> =
  T extends Whitespace ? True : False;

Type-level predicate that checks if a given string T is a whitespace character. If T is a whitespace character, it will resolve to the True type parameter (default: true). Otherwise, it will resolve to the False type parameter (default: false).

The compile-time equivalent of the isWhitespaceChar function.

• T extends string
• True (default: true)
• False (default: false)

export type IsWhitespaceCode<T extends number, True = true, False = false> =
  T extends WhitespaceCode ? True : False;

Type-level predicate that checks if a given string T is a whitespace character code. If T is a whitespace character code, it will resolve to the True type parameter (default: true). Otherwise, it will resolve to the False type parameter (default: false).

The compile-time equivalent of the isWhitespaceCode function.

• T extends number
• True (default: true)
• False (default: false)

export type Whitespace = typeof WHITESPACE_CHARS[number] & {};

A union of all whitespace characters, as defined by the Unicode standard. This includes characters such as spaces, tabs, newlines, and additional Unicode whitespace characters that are not typically visible in text.

This type is particularly useful for type-level programming, specifically when developing string manipulation types that need to account for various types of whitespace characters rather than a simple ASCII space.

For example, if one wanted to create a type-level utility to split a string literal into its constituent parts using whitespace and punctuation as its delimiters, it could be done quite easily using this type.

Types

whitespace

export type WhitespaceCode = typeof WHITESPACE_CODES[number];

Union of all whitespace character codes, as defined by the Unicode standard. This includes characters such as spaces, tabs, newlines, and additional Unicode whitespace characters that are not typically visible.

Types

whitespace char code

export type WhitespaceLike = WhitespaceString | Whitespace | WhitespaceCode;

A union type that can be either a string or a whitespace character code.

This is the type used in the isWhitespaceLike function to determine if a value is either a string or a whitespace character code.

Types

whitespace

export type WhitespaceString<S extends string = string> = S & WhitespaceBrand;

Represents a string that has been verified at runtime to only consist of whitespace characters. This is a nominal (branded) type that is distinct from a regular string type.

• S extends string (default: string)

Types

whitespace branded