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')

Available Types

• 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 Function

Checks if value matches the specified type, then returns the first function (or value) if true or the second function (or value) if false.

Method:

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

Example:

  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 Checks

Array Method:

  is.arr($value)

Example:

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

Bad Method:

  is.bad($value)

Example:

  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

Boolean Method:

  is.bool($value)

Example:

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

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

Date Method:

  is.date($value)

Example:

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

Empty Method:

  is.empty($value)

Example:

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

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

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

Error Method:

  is.err($value)

Example:

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

Function Method:

  is.fn($value)

Example:

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

Integer Method:

  is.int($value)

Example:

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

JSON Method:

  is.json($value)

Example:

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

Null Method:

  is.null($value)

Example:

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

Null or Undefined Method:

  is.noru($value)

Example:

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

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

Number Method:

  is.num($value)

Example:

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

Object Method:

  is.obj($value)

Example:

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

Promise Method:

  is.prom($value)

Example:

  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 Method:

  is.regex($value)

Example:

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

String Method:

  is.str($value)

Example:

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

Symbol Method:

  is.sym($value)

Example:

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

Undefined Method:

  is.undef($value)

Example:

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