string-contains

This is a string inspection utility that is mindful of non-English character sets. A common pattern in JavaScript is to test for the presence of alphabetic characters like this:

const containsOnlyLetters = (string = '') => !!string.match(/^[a-zA-Z]+$/);

But the above code is entirely Anglo-centric, because it assumes that the universe of letters consists of the capitals A-Z and the lowercases a-z. In other words, this approach only checks for the presence of letters in the ASCII range.

Even if an application is not specifically designed to be multilingual, it can be exclusionary (and potentially discriminatory) to force names (or other sensitive data) to conform to ASCII standards.

For example, when prompting a user to enter their last name, many English speakers assume that

Calderón

Is no different than

Calderon

Or that

Núñez

Is no different than

Nunez

But there are many in the Latinx community who feel otherwise.

The same problem often occurs when handling place names - even places in English-speaking countries.

For example, there is no city called

Pinon Hills

in California. But there is a city called

Piñon Hills

And in Minnesota, there is a city commonly referred to as

Lindstrom

But its proper spelling is

Lindström

English speakers may assume that there is no harm in forcing someone with the name of "Núñez" to enter their name as "Nunez". But aside from being potentially discriminatory, these discrepancies can have systemic effects.

For example, it is perfectly valid (albeit, rare) to have non-ASCII values in an email address. So if someone's email address is núñ[email protected], and your validation scripts reject any email addresses with non-ASCII letters, the user would be faced with the choice to either A) enter a non-working email, just to pass the validation, or B) abandon the form altogether.

Similarly, non-ASCII characters can absolutely be in domain names. So restricing non-ASCII characters may keep you from collecting the user's email address or the URL for their website.

Methodology

This utility works by using the Letter and Mark RegEx Unicode character classes.

Usage

import { contains } from '@toolz/string-contains';

const letters = 'úñóö';

const containsLetters = (string = '') => string.match(/[A-Za-z]/);
containsLetters(letters); // returns FALSE

contains.letters(letters); // returns TRUE

Methods

.alphanumerics()

.alphanumerics() determines whether a string contains any alphanumeric values.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
   },
   returns: Boolean,
}

Examples:

const letters = 'úñóö';
const numbers = '122';
const empty = '';
const specialCharacters = '_*%$';

contains.alphanumerics(letters); // returns TRUE
contains.alphanumerics(numbers); // returns TRUE
contains.alphanumerics(empty); // returns FALSE
contains.alphanumerics(specialCharacters); // returns FALSE

.letters()

.letters() determines whether a string contains any letters.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'howdy';

contains.letters(pi); // returns FALSE
contains.letters(russian); // returns TRUE
contains.letters(english); // returns TRUE

.lowercaseLetters()

.lowercaseLetters() determines whether a string contains any lowercase letters.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
   },
   returns: Boolean,
}

Examples:

const uppercaseRussian = 'БЫСТРЫЙЛЕНИВЫЙЛИС';
const mixedCaseEnglish = 'Bill Joe Henry';
const pi = '3.14';

contains.lowercaseLetters(uppercaseRussian); // returns FALSE
contains.lowercaseLetters(mixedCaseEnglish); // returns TRUE
contains.lowercaseLetters(pi); // returns FALSE

.numbers()

.numbers() determines whether a string contains any numbers.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'day number one';

contains.numbers(pi); // returns TRUE
contains.numbers(russian); // returns FALSE
contains.numbers(english); // returns FALSE

.onlyAlphanumerics()

.onlyAlphanumerics() determines whether a string contains only alphanumeric values.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
      ignoredCharacters: {
         optional,
         format: 'array of strings',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'day number 1';

contains.onlyAlphanumerics(pi); // returns FALSE
contains.onlyAlphanumerics(russian); // returns TRUE
contains.onlyAlphanumerics(english); // returns FALSE (because of the spaces)
contains.onlyAlphanumerics(pi, ['.']); // returns TRUE
contains.onlyAlphanumerics(english, [' ']); // returns TRUE

.onlyLetters()

.onlyLetters() determines whether a string contains only letters.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
      ignoredCharacters: {
         optional,
         format: 'array of strings',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'day number one';

contains.onlyLetters(pi); // returns FALSE
contains.onlyLetters(russian); // returns TRUE
contains.onlyLetters(english); // returns FALSE (because of the spaces)
contains.onlyLetters(pi, ['.']); // returns FALSE
contains.onlyLetters(english, [' ']); // returns TRUE

.onlyLowercaseLetters()

.onlyLowercaseLetters() determines whether a string contains only lowercase letters.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
      ignoredCharacters: {
         optional,
         format: 'array of strings',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'day number one';

contains.onlyLowercaseLetters(pi); // returns FALSE
contains.onlyLowercaseLetters(russian); // returns FALSE
contains.onlyLowercaseLetters(english); // returns FALSE (because of the spaces)
contains.onlyLowercaseLetters(pi, ['.']); // returns FALSE
contains.onlyLowercaseLetters(english, [' ']); // returns TRUE

.onlyNumbers()

.onlyNumbers() determines whether a string contains only numbers.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
      ignoredCharacters: {
         optional,
         format: 'array of strings',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'day number one';

contains.onlyNumbers(pi); // returns FALSE
contains.onlyNumbers(russian); // returns FALSE
contains.onlyNumbers(english); // returns FALSE (because of the spaces)
contains.onlyNumbers(pi, ['.']); // returns TRUE
contains.onlyNumbers(english, [' ']); // returns FALSE

.onlyUppercaseLetters()

.onlyUppercaseLetters() determines whether a string contains only uppercase letters.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
      ignoredCharacters: {
         optional,
         format: 'array of strings',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'DAY ONE';

contains.onlyUppercaseLetters(pi); // returns FALSE
contains.onlyUppercaseLetters(russian); // returns FALSE
contains.onlyUppercaseLetters(english); // returns FALSE (because of the space)
contains.onlyUppercaseLetters(pi, ['.']); // returns FALSE
contains.onlyUppercaseLetters(english, [' ']); // returns TRUE

.specialCharacters()

.specialCharacters() determines whether a string contains any nonalphanumeric values.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
      ignoredCharacters: {
         optional,
         format: 'array of strings',
      },
   },
   returns: Boolean,
}

Examples:

const pi = '3.14';
const russian = 'быстрыйленивыйлис';
const english = 'DAY ONE';

contains.specialCharacters(pi); // returns TRUE
contains.specialCharacters(russian); // returns FALSE
contains.specialCharacters(english); // returns TRUE (because of the space)
contains.specialCharacters(pi, ['.']); // returns FALSE
contains.specialCharacters(english, [' ']); // returns FALSE

.uppercaseLetters()

.uppercaseLetters() determines whether a string contains any uppercase letters.

const API = {
   arguments: {
      string: {
         required,
         format: 'string',
      },
   },
   returns: Boolean,
}

Examples:

const uppercaseRussian = 'БЫСТРЫЙЛЕНИВЫЙЛИС';
const mixedCaseEnglish = 'Bill Joe Henry';
const pi = '3.14';

contains.uppercaseLetters(uppercaseRussian); // returns TRUE
contains.uppercaseLetters(mixedCaseEnglish); // returns TRUE
contains.uppercaseLetters(pi); // returns FALSE