Type checking differently
Download the CJS, ESM, UMD versions or install via NPM:
npm install @ryanmorr/kindRather than relying on the common "is" functions such as isArray, isString, etc., kind uses type constants to create a versatile approach that supports type assertions, identification, and customization:
import { kind, KIND_STRING, KIND_NULL, KIND_UNDEFINED } from '@ryanmorr/kind';
// Assert a type match
kind('foo', KIND_STRING); //=> true
// Assert at least one match from a group of types
kind(null, [KIND_NULL, KIND_UNDEFINED]); //=> true
// Identify a type
kind(123); //=> KIND_NUMBERYou can define a custom type via def, providing a function to detect that type (must return a boolean):
import { def, kind, KIND_FUNCTION } from '@ryanmorr/kind';
const fn = async () => 1;
// Define a custom type for async functions
const KIND_ASYNC_FUNCTION = def((obj) => {}.toString.call(obj) == '[object AsyncFunction]');
// Will return true for the new type
kind(fn, KIND_ASYNC_FUNCTION); //=> true
// Will still return true for any other matching type
kind(fn, KIND_FUNCTION); //=> true
// When identifying an object type, custom types are always tested first
kind(fn); //=> KIND_ASYNC_FUNCTIONYou can also define type groups by providing an array of sub-types:
import { def, kind, KIND_STRING, KIND_NUMBER, KIND_BOOLEAN } from '@ryanmorr/kind';
// Define a custom group type
const KIND_PRIMITIVE = def([KIND_STRING, KIND_NUMBER, KIND_BOOLEAN]);
// Will return true if the object matches at least one of the sub-types
kind(123, KIND_PRIMITIVE); //=> true
kind('foo', KIND_PRIMITIVE); //=> true
kind(false, KIND_PRIMITIVE); //=> true
// Group types will never be identified as an object type
kind(789); //=> KIND_NUMBERKind comes with the following built-in default types:
KIND_NULLKIND_UNDEFINEDKIND_STRINGKIND_BOOLEANKIND_NANKIND_NUMBERKIND_SYMBOLKIND_PLAIN_OBJECTKIND_OBJECTKIND_ARRAYKIND_FUNCTIONKIND_SETKIND_WEAK_SETKIND_MAPKIND_WEAK_MAPKIND_ITERABLEKIND_REGEXPKIND_DATEKIND_ERRORKIND_PROMISEKIND_GLOBALKIND_UNKNOWN
This project is dedicated to the public domain as described by the Unlicense.