@klyper/types

Shared TypeScript type aliases and runtime type guards for Klyper packages.

Use this package when a module needs small, dependency-free helpers for narrowing unknown values or reusing common utility types.

Installation

npm install @klyper/types

This package is published as an ES module package and also exposes a CommonJS entry through main.

Usage

import { isPlainObject, isString, type } from "@klyper/types";

const value: unknown = { title: "Klyper" };

if (isPlainObject(value) && isString(value.title)) {
  value.title.toUpperCase();
}

type(value); // "object"

The runtime helpers accept unknown values and return TypeScript type predicates where possible.

Runtime API

Type detection

| Export | Description | | --- | --- | | type(value) | Returns a normalized logical type name. null and undefined both return "null". |

Recognized logical type names include "array", "asyncfunction", "bigint", "boolean", "date", "error", "function", "map", "null", "number", "object", "promise", "regexp", "set", "string", "symbol", "weakmap", and "weakset".

Type guards

| Export | Narrows to | Notes | | --- | --- | --- | | isArray(value) | Array<any> | Checks array values. | | isAsyncFunction(value) | TypeAnyAsyncFunction | Checks functions declared with async. | | isBigInt(value) | bigint | Checks bigint primitives. | | isBoolean(value) | boolean | Checks boolean primitives. | | isConstructor(value) | TypeAnyConstructor | Checks functions whose prototype constructor points back to the function. | | isDate(value) | Date | Checks Date instances. | | isDef<T>(value) | T | Returns false for null and undefined. | | isError(value) | Error | Checks Error instances. | | isFiniteNumber(value) | number | Checks finite number primitives. | | isFloat(value) | number | Checks finite numbers with a fractional part. | | isFunction(value) | TypeAnyFunction | Checks callable values. | | isInteger(value) | number | Checks integer number primitives. | | isMap<K, V>(value) | Map<K, V> | Checks Map instances. | | isNil(value) | null \| undefined | Checks only null and undefined. | | isNonEmptyArray<T>(value) | [T, ...Array<T>] | Checks arrays with at least one item. | | isNull(value) | null | Checks only null. | | isNumber(value) | number | Checks number primitives, including NaN and infinities. | | isNumberLike(value) | boolean | Checks strings that represent finite decimal numbers. Scientific, binary, hex, NaN, and Infinity strings are rejected. | | isObject(value) | TypeAnyObject | Checks values whose normalized logical type is "object", including object literals, Object.create(null), and class instances. Arrays, maps, sets, dates, and regexps are excluded. | | isPlainObject(value) | TypeAnyObject | Checks object literals and Object.create(null) values. Class instances are excluded. | | isPromise<T>(value) | Promise<T> | Checks Promise instances, not arbitrary thenables. | | isRegExp(value) | RegExp | Checks regular expressions. | | isScalar(value) | TypeScalar | Checks boolean, number, and string values. | | isSet<T>(value) | Set<T> | Checks Set instances. | | isString(value) | string | Checks string primitives. | | isSymbol(value) | symbol | Checks symbol primitives. | | isUndefined(value) | undefined | Checks only undefined. |

Type Aliases

Common exported type aliases include:

import type {
  TypeAnyAsyncFunction,
  TypeAnyConstructor,
  TypeAnyFunction,
  TypeAnyObject,
  TypeCallback,
  TypeNullable,
  TypeName,
  TypeObjectOptional,
  TypeObjectRequired,
  TypeScalar,
} from "@klyper/types";

Notable groups:

• Array aliases: TypeArray, TypeAnyArray, TypeFunctionArray, TypeNumberArray, TypeObjectArray, and TypeStringArray.
• Object aliases: TypeObject, TypeAnyObject, TypeBooleanObject, TypeFunctionObject, TypeNumberObject, and TypeStringObject.
• Object shape helpers: TypeObjectOptional, TypeObjectRequired, TypeObjectKeys, and TypeObjectKeysFunction.
• Callback aliases: TypeCallback, TypeCallbackArray, TypeCallbackMap, and TypeCallbackObject.
• Value helpers: TypeKey, TypeNullable, TypeOptional, and TypeScalar.

Primitive guards such as isString, isNumber, isBoolean, isBigInt, and isSymbol only accept primitives. Boxed wrappers such as new String("x"), new Number(1), and new Boolean(false) return false.

Commands

npm run build --workspace @klyper/types
npm run check --workspace @klyper/types
npm run lint --workspace @klyper/types
npm test --workspace @klyper/types

build uses Rollup for the package output. check runs TypeScript without emitting files.

Validation

Run the package checks before publishing or changing exports:

npm run check --workspace @klyper/types
npm test --workspace @klyper/types