@orkestrel/validator

Focused, composable runtime type guards for TypeScript (ESM‑only).

• TypeScript‑first, strict by default (no any, safe narrowing from unknown)
• Deterministic, tiny helpers that only narrow types meaningfully
• Portable: browser + Node compatible; tests use Vitest

Repository: https://github.com/orkestrel/validator

Contents

• Install
• Quick start
• Guards
• TypeScript and build
• Contributing
• License

Install

npm i @orkestrel/validator

Requirements

• Node 18+ (for tests), TypeScript 5+
• ESM‑only (package.json "type": "module"); moduleResolution: bundler

Quick start

import { isRecord, isString, isArray, isNumber } from '@orkestrel/validator'

const input: unknown = JSON.parse('{"id":"u1","tags":["x","y"],"count":1}')

if (isRecord(input) && isString(input.id) && isArray(input.tags) && input.tags.every(isString) && isNumber(input.count)) {
  // id: string, tags: readonly string[], count: number
}

Quick start (schema builders)

import { objectOf, arrayOf } from '@orkestrel/validator'
import { isString, isNumber } from '@orkestrel/validator'

const input: unknown = JSON.parse('{"id":"u1","tags":["x","y"],"count":1}')

const Payload = objectOf({
  id: isString,
  tags: arrayOf(isString),
  count: isNumber,
})

if (Payload(input)) {
  // input is now narrowed with id/tags/count
}

Guards

• Primitives: isNull, isUndefined, isDefined, isString, isNumber, isBoolean, isBigInt, isSymbol, isFunction, isDate, isRegExp, isError, isPromise, isPromiseLike, isArrayBuffer, isSharedArrayBuffer, isIterable, isAsyncIterator
• Arrays & views: isArray, isArrayBufferView, typed arrays (isInt8Array, isUint8Array, isUint8ClampedArray, isInt16Array, isUint16Array, isInt32Array, isUint32Array, isFloat32Array, isFloat64Array, isBigInt64Array, isBigUint64Array), isDataView
• Collections & objects: isObject, isMap, isSet, isWeakMap, isWeakSet, isRecord
• Emptiness: isEmptyString, isEmptyArray, isEmptyObject, isEmptyMap, isEmptySet, isNonEmptyString, isNonEmptyArray, isNonEmptyObject, isNonEmptyMap, isNonEmptySet
• Function introspection: isZeroArg, isAsyncFunction, isGeneratorFunction, isAsyncGeneratorFunction, isZeroArgAsync, isZeroArgGenerator, isZeroArgAsyncGenerator
• Schema & combinators: arrayOf, tupleOf, objectOf (second param optional supports true or a key array), mapOf, setOf, recordOf, iterableOf, literalOf, enumOf, keyOf, pickOf, omitOf, andOf, orOf, notOf, complementOf, unionOf, intersectionOf, composedOf, whereOf, lazyOf, transformOf, nullableOf, instanceOf

Each function accepts unknown (or the relevant supertype) and returns a precise x is T predicate for meaningful narrowing.

TypeScript and build

Recommended TS config (excerpt):

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "lib": ["ESNext", "DOM"],
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true
  }
}

ESM‑only usage in Node:

node --version

Contributing

We value determinism, strict typing, and small, composable APIs. See guides/contribute.md for principles and workflow.

License

MIT © Orkestrel