@pfeiferio/check-primitives

Minimal, strict runtime type checks for JavaScript / TypeScript.

This package provides primitive validation helpers that:

• do not coerce values
• throw deterministic errors
• are framework-agnostic
• are designed for infrastructure and boundary validation

Installation

npm install @pfeiferio/check-primitives

Usage

Checks (return value or throw)

import {checkString, checkNumber} from '@pfeiferio/check-primitives'

const name = checkString(input.name)
const age = checkNumber(input.age)

Assertions (type narrowing)

import {assertObject, assertString} from '@pfeiferio/check-primitives'

assertObject(payload)
assertString(payload.name)

// payload is now typed safely

Included checks

• checkString
• checkNumber (finite only)
• checkBoolean
• checkArray
• checkObject (plain object)
• checkFunction
• checkNull
• checkUndefined

Each check has a corresponding assert* variant.

Errors

All checks throw a ValidationError with a stable error code.

try {
  checkNumber(value)
} catch (err) {
  if (err instanceof ValidationError) {
    console.log(err.code)
  }
}

Philosophy

This package intentionally does not include:

• format validation
• length or range constraints
• coercion or defaults
• schemas or DSLs

It is meant to be used as a low-level building block.

License

MIT