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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 18K minified (4.5K gzipped, 4.1K brotli-ified).

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
  • anyTypeValidator
  • array (alias of arrayOfUnknown)
  • arrayOf
  • arrayOfAny
  • arrayOfUnknown
  • Array (alias of arrayOfUnknown)
  • assertType (assert that a value has the provided type, and throw an error message if it doesn't)
  • asType (do a TypeScript as cast to convert the value into the provided type)
  • bigint
  • BigInt (alias of bigint)
  • boolean
  • Boolean (alias of boolean)
  • Date
  • Error
  • exactBigInt
  • exactNumber
  • exactString
  • exactSymbol
  • false
  • falsy
  • Function (alias of unknownFunction)
  • hasClassName
  • hasToStringTag
  • Infinity
  • instanceOf
  • integer
  • intersection
  • isOfType (return a boolean indicating if a value is of the provided type)
  • map (alias of unknownMap)
  • Map (alias of unknownMap)
  • mapOf
  • mappingObjectOf
  • maybe
  • NaN
  • NegativeInfinity
  • never
  • nonNullOrUndefined
  • null
  • nullish
  • void (alias of nullish)
  • number (doesn't include NaN, Infinity, or -Infinity)
  • Number (alias of number)
  • numberIncludingNanAndInfinities
  • object (alias of unknownObject)
  • Object (alias of unknownObject)
  • objectOrNull
  • objectWithOnlyTheseProperties
  • objectWithProperties
  • or
  • optional
  • partialObjectWithProperties
  • record
  • RegExp
  • set (alias of unknownSet)
  • Set (alias of unknownSet)
  • setOf
  • string
  • String (alias of string)
  • stringifyValue (safe and lightweight value-to-string function, for printing values in error messages)
  • stringMatching
  • Symbol
  • symbol (alias of Symbol)
  • symbolFor
  • true
  • truthy
  • tuple
  • undefined
  • union
  • unknown
  • unknownFunction
  • unknownMap
  • unknownObject
  • unknownSet
  • unknownTypeValidator
  • ArrayBuffer
  • SharedArrayBuffer
  • DataView
  • TypedArray
  • Int8Array
  • Uint8Array
  • Uint8ClampedArray
  • Int16Array
  • Uint16Array
  • Int32Array
  • Uint32Array
  • Float32Array
  • Float64Array

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