Tagged types

The library implements various string sub-type helpers. They might be useful for cases when we want type safety for emails, URLs, BICs, IBANs or other string types. Each subtype module exposes the type and a set of basic functions to work with it, like cast, isTypeof and assert.

The package is organized into submodules, each can be imported separately.

Installation

npm

npm install @kilbergr/tagged-types

yarn

yarn add @kilbergr/tagged-types

Importing

import { BIC, type bic } from '@kilbergr/tagged-types/bic';
import { Email, type email } from '@kilbergr/tagged-types/email';

Usage

// Use the type in your code
let myBic: bic;
let myEmail: email;

// Cast a string to the type
myBic = BIC('DEUTDEFF500');
myEmail = Email('[email protected]');

// Check if a string is of the type
if (BIC.isTypeof(myBic)) {
  ...
}

if (Email.isTypeof(myEmail)) {
  ...
}

// Assert a string is of the type
BIC.assert(myBic);
Email.assert(myEmail);

Some string sub-types compose multiple information and implement parse and from functions to work with them.

const { bankCode, branchCode, locationCode, countryCode } = BIC.parse(myBic);