I.E. (Id Est)

Runtime type definitions for TypeScript with validation, target-based conversions, and decorator-powered metadata.

Features

• Runtime types for primitives, objects, tuples, unions, literals, enumerations, arrays, binary data, dates, and constructable classes.
• Validate unknown values at runtime via type.is(value).
• Convert values to/from well-known targets (for example json and shallowSnapshot) via type.to.<target> / type.from.<target>.
• Decorate class properties/parameters with runtime types and build a constructable type from metadata.

Installation

npm install @aliaksandarpratashchyk/ie

Quick start

import ie from '@aliaksandarpratashchyk/ie';

const userType = ie.object({
  id: ie.string,
  age: ie.optional.number,
  tags: ie.array.string,
});

const user = {
  id: '42',
  age: undefined,
  tags: ['admin'],
};

if (!userType.is(user)) throw new Error('Invalid user');

const jsonSnapshot = userType.to.json(user);
const rehydrated = userType.from.json(jsonSnapshot);

Conversions

Each built-in type lists which targets it supports (for example, ie.number.from.string('42') or ie.bigint.to.string(42n)):

import ie from '@aliaksandarpratashchyk/ie';

const n = ie.number.from.string('42');
const s = ie.bigint.to.string(42n);

Decorators

Attribute helpers let you attach runtime types to class properties or parameters:

import ie from '@aliaksandarpratashchyk/ie';
import { number, optional, string } from '@aliaksandarpratashchyk/ie/attributes';

class User {
  @string
  name!: string;

  @number
  score!: number;

  @optional.string
  bio?: string;
}

const userType = ie.constructable(User);

Built-in types

• Primitives: ie.string, ie.number, ie.boolean, ie.bigint, ie.date, ie.null, ie.undefined
• Binary: ie.binary (a Uint8Array / Node.js Buffer; ie.binary.to.json uses base64)
• Wrappers: ie.optional(type) / ie.nullable(type) (also available as ie.optional.string, ie.nullable.number, ...)
• Collections: ie.array(type), ie.tuple(...), ie.union(...), ie.object(schema)
• Literals/enumerations: ie.literal(value), ie.enumeration(...)
• Classes: ie.constructable(SomeClass)

See ie.api.md for the full public surface (generated by API Extractor).

Scripts

• npm test — run the Jest suite, regenerate COVERAGE.md, and update coverage.svg.
• npm run build — bundle the library and regenerate API docs (docs/).
• npm run lint / npm run format — lint and format the codebase.

Publishing

GitHub Actions runs tests on pushes/PRs and publishes to npm when the version in package.json changes on main. Set NPM_TOKEN in repository secrets to enable publishing.