pheno

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 21K minified (5.0K gzipped, 4.4K brotli-ified), but can be even smaller if your bundler supports tree-shaking.

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