tonivj5 / pheno

Simple, lightweight at-runtime type checking functions, with full TypeScript support

pheno

Simple, lightweight at-runtime type checking functions, with full TypeScript support

Features

• Full TypeScript integration: TypeScript understands that assertType and isOfType narrow the types of things, and will refine them accordingly
• Simple: Type validators are just functions that return booleans.
• Effective: There's lots of utility functions that help you represent all the various types you'd care about in your code.
• Lightweight: The whole library is 24K minified (before gzip/brotli), but it's also fully tree-shakeable, so only the type validators you use end up in your bundle.

Usage Example

import * as types from "pheno";

function something(first: unknown, second: unknown) {
  // Throws an error if `first` is not a string
  types.assertType(first, types.string);

  // Throws an error if `second` is not `string | number`
  types.assertType(second, types.union(types.string, types.number));

  // Typescript now knows that `first` is a string and `second` is `string | number`
  return first + " " + String(second);
}

List of types and type builder functions

• and
• any
• anyArray
• anyFunction
• anyMap
• anyObject
• anySet
• array
• arrayOf
• arrayOfAny
• arrayOfUnknown
• assertType
• asType
• boolean
• Error_
• exactNumber
• exactString
• false_
• falsy
• hasClassName
• Infinity_
• instanceOf
• integer
• intersection
• isOfType
• map
• mapOf
• mappingObjectOf
• maybe
• NaN_
• NegativeInfinity
• never
• nonNullOrUndefined
• null_
• nullish
• number
• numberIncludingNanAndInfinities
• object
• objectWithOnlyTheseProperties
• objectWithProperties
• or
• partialObjectWithProperties
• record
• set
• setOf
• string
• stringMatching
• Symbol_
• symbolFor
• true_
• truthy
• tuple
• undefined_
• union
• unknown
• unknownFunction
• unknownMap
• unknownObject
• unknownSet

Please see the TypeScript types for each of these in either your editor's autocomplete or pheno's source code for more information.

License

MIT