A port of ActiveSupport's inflector to Node.js. Also usable in the browser. Forked from inflected and modified to use TypeScript and improve performance.

Install via npm:

% npm install superflected

Or via pnpm:

% pnpm add superflected

The module exports an object with several utility functions.

import { pluralize } from "superflected";

pluralize("Category"); // => 'Categories'

Here is the complete API reference:

pluralize(word: string, locale?: string): string

Returns the plural form of the word in the string.

If passed an optional locale parameter, the word will be pluralized using rules defined for that language. By default, this parameter is set to "en".

pluralize("post"); // => 'posts'
pluralize("octopus"); // => 'octopi'
pluralize("sheep"); // => 'sheep'
pluralize("words"); // => 'words'
pluralize("CamelOctopus"); // => 'CamelOctopi'
pluralize("ley", "es"); // => 'leyes'

singularize(word: string, locale?: string): string

The reverse of pluralize, returns the singular form of a word in a string.

If passed an optional locale parameter, the word will be singularized using rules defined for that language. By default, this parameter is set to "en".

singularize("posts"); // => 'post'
singularize("octopi"); // => 'octopus'
singularize("sheep"); // => 'sheep'
singularize("word"); // => 'word'
singularize("CamelOctopi"); // => 'CamelOctopus'
singularize("leyes", "es"); // => 'ley'

camelize(term: string, uppercaseFirstLetter?: boolean): string

By default, camelize converts strings to UpperCamelCase. If the second argument is set to false then camelize produces lowerCamelCase.

camelize("foo_bar"); // => 'FooBar'
camelize("foo_bar", false); // => 'fooBar'

As a rule of thumb you can think of camelize as the inverse of underscore, though there are cases where that does not hold:

camelize(underscore("SSLError")); // => 'SslError'

underscore(camelCasedWord: string): string

Makes an underscored, lowercase form from the expression in the string.

underscore("FooBar"); // => 'foo_bar'

As a rule of thumb you can think of underscore as the inverse of camelize, though there are cases where that does not hold:

camelize(underscore("SSLError")); // => 'SslError'

humanize(lowerCaseAndUnderscoredWord: string, options?: object): string

Capitalizes the first word, turns underscores into spaces, and strips a trailing "_id" if present.

Like titleize, this is meant for creating pretty output.

The capitalization of the first word can be turned off by setting the capitalize option key to false. By default, this option is true.

humanize("employee_salary"); // => 'Employee salary'
humanize("author_id"); // => 'Author'
humanize("author_id", { capitalize: false }); // => 'author'

titleize(sentence: string): string

Capitalizes all the words and replaces some characters in the string to create a nicer looking title. titleize is meant for creating pretty output.

titleize("man from the boondocks"); // => 'Man From The Boondocks'
titleize("x-men: the last stand"); // => 'X Men: The Last Stand'
titleize("TheManWithoutAPast"); // => 'The Man Without A Past'
titleize("raiders_of_the_lost_ark"); // => 'Raiders Of The Lost Ark'

tableize(className: string): string

Create the name of a table like Rails does for models to table names. This method uses the pluralize method on the last word in the string.

tableize("RawScaledScorer"); // => 'raw_scaled_scorers'
tableize("egg_and_ham"); // => 'egg_and_hams'
tableize("fancyCategory"); // => 'fancy_categories'

classify(tableName: string): string

Create a class name from a plural table name like Rails does for table names to models.

classify("egg_and_hams"); // => 'EggAndHam'
classify("posts"); // => 'Post'

Singular names are not handled correctly:

classify("business"); // => 'Busines'

dasherize(underscoredWord: string): string

Replaces underscores with dashes in the string.

dasherize("puni_puni"); // => 'puni-puni'

foreignKey(className: string, separateClassNameAndIdWithUnderscore?: boolean): string

Creates a foreign key name from a class name. separateClassNameAndIdWithUnderscore sets whether the method should put "_" between the name and "id" (default: true).

foreignKey("Message"); // => 'message_id'
foreignKey("Message", false); // => 'messageid'

ordinal(number: number): string

Returns the suffix that should be added to a number to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.

ordinal(1); // => 'st'
ordinal(2); // => 'nd'
ordinal(1002); // => 'nd'
ordinal(1003); // => 'rd'
ordinal(-11); // => 'th'
ordinal(-1021); // => 'st'

ordinalize(number: number): string

Turns a number into an ordinal string used to denote the position in an ordered sequence such as 1st, 2nd, 3rd, 4th.

ordinalize(1); // => '1st'
ordinalize(2); // => '2nd'
ordinalize(1002); // => '1002nd'
ordinalize(1003); // => '1003rd'
ordinalize(-11); // => '-11th'
ordinalize(-1021); // => '-1021st'

inflections([string locale])

Get the inflections object for a given locale. The result can be modified to add additional inflection rules.

import { inflections } from "superflected";
const inflect = inflections('en')
inflect.plural(/^(ox)$/i, '$1$2en');
inflect.singular /^(ox)en/i, '$1');

inflect.irregular('octopus', 'octopi');

inflect.uncountable('equipment', 'snow');

New rules are added at the top. So in the example above, the irregular rule for octopus will now be the first of the pluralization and singularization rules that is run. This guarantees that your rules run before any of the rules that may already have been loaded.

transliterate(sentence: string, options?: object): string

Replaces non-ASCII characters with an ASCII approximation, or if none exists, a replacement character which defaults to "?".

transliterate("Ærøskøbing"); // => 'AEroskobing'

Default approximations are provided for Western/Latin characters, e.g, "ø", "ñ", "é", "ß", etc.

This method is I18n-aware, so you can set up custom approximations for a locale. This can be useful, for example, to transliterate German's "ü" and "ö" to "ue" and "oe", or to add support for transliterating Russian to ASCII.

In order to make your custom transliterations available, you must set them using the approximate helper function:

import { transliterations } from "superflected";
const transliterator = transliterations("de");
transliterator.approximate("ü", "ue");
transliterator.approximate("ö", "oe");

Now you can have different transliterations for each locale:

transliterate("Jürgen"); // => 'Jurgen'
transliterate("Jürgen", { locale: "de" }); // => 'Juergen'

parameterize(sentence: string, options?: { separator?: string, preserveCase?: boolean }): string

Replaces special characters in a string so that it may be used as part of a 'pretty' URL.

parameterize("Donald E. Knuth"); // => 'donald-e-knuth'
parameterize("Donald E. Knuth", { separator: "+" }); // => 'donald+e+knuth'

There's a preserveCase option:

parameterize("Donald E. Knuth", { preserveCase: true }); // => 'Donald-E-Knuth'

constantify(words: string): string

Converts words (camelCased, under_scored, or dasherized) to CONSTANT_CASE.

constantify("bankAccount"); // => 'BANK_ACCOUNT'
constantify("bank-account"); // => 'BANK_ACCOUNT'
constantify("bank_account"); // => 'BANK_ACCOUNT'
constantify("Bank Account"); // => 'BANK_ACCOUNT'

superflected recomputes the result of any inflections each time you make them by default. If you know ahead of time that you'll be calling with particular high volume inputs, you can use the built in caching helpers to pin results in memory and avoid recomputation. This is just a built in memoizer that is as high performance as possible.

To prepopulate the cache, call populate on the function you'd like to cache.

import { camelize } from "superflected";
camelize.populate("foo_bar"); // will store the result of camelize("foo_bar") in memory
camelize("foo_bar"); // will return the cached result instead of recomputing

Here's a quick guide:

1. Fork the repo and pnpm install.
2. Run the tests. We only take pull requests with passing tests, and it's great to know that you have a clean slate: pnpm test.
3. Add a test for your change. Only refactoring and documentation changes require no new tests. If you are adding functionality or are fixing a bug, we need a test!
4. Make the test pass.
5. Push to your fork and submit a pull request.

Released under The MIT License.