typa

Typa

A super-simple JavaScript type checker. Mainly pilfered from this blog post by Webbjocke. No dependencies. 3.6K GCC compiled, 2.0K uncompiled.

Install

npm install typa

Import

import {is} from 'typa'

/* or */

const is = require('typa')

Quick Start

const hello = 'Hello!'
const goodbye = ['Goodbye!', 'Adios!', 'Au revoir!']

if (is.str(hello)) console.log(hello)
  // => 'Hello!'

if (is.str(goodbye)) console.log(hello)
  // => no result

API

• arr → Array
• bad → Null, undefined, empty, or an error
• bool → Boolean
• date → Date
• empty → Empty string, array, or object
• err → Error
• fn → Function
• int → Integer
• json → Serialized JSON object
• nll → Null
• noru → Null or undefined
• num → Number
• obj → Object
• prom → Promise
• regex → Regular expression
• str → String
• sym → Symbol
• undef → Undefined

Typa Method

Ternary function that checks if the supplied value matches the specified type, then returns the first function (or value) if true or the second function (or value) if false.

.typa($type, $value, $fn1, $fn2)

  const myString = 'this is a string'
  const myArray = 'this is also a string, not an array'

  const fn1 = (() => console.log('hello'))
  const fn2 = (() => console.log('goodbye'))

  is.typa('str', myString, fn1, fn2)
    // => 'hello'

  is.typa('arr', myArray, fn1, fn2)
    // => 'goodbye'

Individual Methods

.arr($value) — Array

const isArray = is.arr(['text', 12])
  // => true

.bad($value) — Null, undefined, empty, or an error

let isBad = is.bad(null)
  // => true

isBad = is.bad(undefined)
  // => true

isBad = is.bad({})
  // => true

isBad = is.bad(new Error('This is an error'))
  // => true

.bool($value) — Boolean

let isBool = is.bool(true)
  // => true

isBool = is.bool(false)
  // => true

.date($value) — Date

const isDate = is.date(new Date())
  // => true

.empty($value) — Empty string, array, or object

let isEmpty = is.empty('')
  // => true

isEmpty = is.empty([])
  // => true

isEmpty = is.empty({})
  // => true

.err($value) — Error

const isErr = is.err(new Error('This is an error.'))
  // => true

.fn($value) — Function

const isFn = is.fn(() => { console.log('Hi!') })
  // => true

.int($value) — Integer

const isInt = is.int(12)
  // => true

.json($value) — Serialized JSON object

const isJson = is.json('{"key": "value"}')
  // => true

.nll($value) — Null

const isNll = is.nll(null)
  // => true

.noru($value) — Null or Undefined

let isNoru = is.noru(null)
  // => true

isNoru = is.noru(undefined)
  // => true

.num($value) — Number

const isNum = is.num(28.2)
  // => true

obj($value) — Object

const isObj = is.obj({ key: 'value' })
  // => true

.prom($value) — Promise

const myPromise = new Promise((resolve, reject) => {
  try {
    console.log('I make a promise to you')
    resolve()
  } catch(err) {
    reject(err)
  }
})

const isProm = is.prom(myPromise)
  // => true

.regex($value) — Regular Expression

const isRegex = is.regex(new Regex(/\W/))
  // => true

.str($value) — String

const isStr = is.str('text')
  // => true

.sym($value) — Symbol

const isSym = is.sym(Symbol(42))
  // => true

.undef($value) — Undefined

const isUndef = is.undef(undefined)
  // => true