typetags

String representations of objects in Node.js

Usage no npm install needed!

<script type="module">
  import typetags from 'https://cdn.skypack.dev/typetags';
</script>

README

Node.js Object TypeTags

String representations of objects in Node.js

This package contains a list of default string representations of objects in Node.js, as returned from Object.prototype.toString.call(value) — see the full list here.

Installation

NPM

npm install typetags

Yarn

yarn add typetags

Check the reference here

Usage ⚡️

Typetags

The TypeTags object contains a list of strings, each representing an object type. You can use it to check if an object's typetag matches the default tag of its data type.

import { TypeTags } from 'typetags'

const o = { foo: 'bar' }

if (o.toString() !== TypeTags.Object) {
  doSomething()
}

Helpers

The getTag function can be used to retrieve an object's typetag. Behind the curtains, all it does is to call Object.prototype.toString over any value and return the result.

const { getTag } = require('typetags')

const o = { foo: 'bar' }

const tag = getTag(o)

console.log(tag) // → '[object Object]'

Predicates

There are two kinds of predicate functions to help us with assertions: generics and specifics.

Generics

Used for overall checks. For example, to check if an object has a default typetag:

const { isDefaultTag } = require('typetags')

const o = Object.create(null)

isDefaultTag(o) // → false

Specifics

Allows us to check for specific tags:

const { isArrayTag, getTag } = require('typetags')

const arr = [1, 2, 3]
const tag = arr.toString() // → 1,2,3

isArrayTag(tag) // → false

// however
console.log(getTag(arr)) // → '[object Array]'

Check this page for a reference list of all predicates

Using typetags to detect object class

Every object has a toString() method that is automatically called when the object is to be represented as a text value or when an object is referred to in a manner in which a string is expected.

By default, the toString() method is inherited by every object descended from Object. If this method is not overridden in a custom object, toString() returns "[object type]", where type is the object type. The following code illustrates this:

const o = new Object()
o.toString() // → [object Object]

See Mozilla MDN Web Docs

Although using toString() in this way is unreliable, as objects can change the behavior of Object.prototype.toString() this library might be helpful when you need to compare objects' tags inside a procedure call or if you just need a quick reference.

const { TypeTags, getTag } = require('typetags')

function isArray(value) {
  return typeof value === 'object' && getTag(value) === TypeTags.Array
}

Bundles

esm

import { isDefaultTag } from 'typetags'

cjs

const { isDefaultTag } = require('typetags')

umd

<script src="dist/umd/typetags.min.js"></script>

Reference

TypeTags

  • Object containing all available tags
import { TypeTags } from 'typetags'

console.log(TypeTags.Array) // → [object Array]
console.log(TypeTags.Function) // → [object Function]
console.log(TypeTags.Float64Array) // → [object Float64Array]

Predicates

It has convenience methods to assert objects' type tags:

isDefaultTag() ⚡️
  • Checks if a string is a native default tag
import { isDefaultTag } from 'typetags'

console.log(isDefaultTag('[object Hey]')) // → false
console.log(isDefaultTag('[object Function]')) // → true
Click to See All Available Predicates

String → Boolean

isAbortControllerTag() ⚡️
  • Checks if value is a default AbortController typetag
const { isAbortControllerTag, getTag } = require('typetags')

let abort = new AbortController()
let tag = getTag(abort)

console.log(isAbortControllerTag(abort.toString())) // → true
console.log(isAbortControllerTag(tag)) // → true
isAbortSignalTag() ⚡️
  • Checks if value is a default AbortSignal typetag
const { isAbortSignalTag, getTag } = require('typetags')

let abort = new AbortControllerl()
let tag = getTag(abort.signal)

console.log(isAbortSignalTag(tag)) // → true
console.log(isAbortSignalTag(abort.signal.toString())) // → true
isAggregateErrorTag() ⚡️
  • Checks if value is a default AggregateError typetag
const { isAggregateErrorTag, getTag } = require('typetags')

let err = new AggregateError([])
let tag = getTag(err)

console.log(isAggregateErrorTag(err.toString())) // → false
console.log(isAggregateErrorTag(tag)) // → true
isArgumentsTag() ⚡️
  • Checks if value is a default arguments typetag
const { isArgumentsTag, getTag } = require('typetags')

let tag
;(function any() {
  tag = getTag(arguments)
  return
})()

console.log(isArgumentsTag(tag)) // → true
console.log(isArgumentsTag('[object Function]')) // → false
isArrayTag() ⚡️
  • Checks if value is a default Array typetag
const { isArrayTag, getTag } = require('typetags')

let arr = []

console.log(isArrayTag(arr.toString()) // → false
console.log(isArrayTag(getTag(arr))) // → true
isArrayIteratorTag() ⚡️
  • Checks if value is a default Array Iterator typetag
const { isArrayIteratorTag, getTag } = require('typetags')

let iterator = [][Symbol.iterator]()

console.log(isArrayIteratorTag(iterator.toString()) // → true
console.log(isArrayIteratorTag(getTag(iterator))) // → true
isArrayBufferTag() ⚡️
  • Checks if value is a default ArrayBuffer typetag
const { isArrayBufferTag } = require('typetags')

let buf = new ArrayBuffer(8)

console.log(isArrayBufferTag(buf.toString())) // → true
console.log(isArrayBufferTag('[object Array]')) // → false
isAsyncFunctionTag() ⚡️
  • Checks if value is a default AsyncFunction typetag
const { isAsyncFunctionTag, getTag } = require('typetags')

let fn = async () => 'oh, hi!'
let typetag = getTag(fn)

console.log(isAsyncFunctionTag(fn.toString())) // → false
console.log(isAsyncFunctionTag(typetag)) // → true
isAtomicsTag() ⚡️
  • Checks if value is a default Atomics typetag
const { isAtomicsTag } = require('typetags')

const buffer = new SharedArrayBuffer(16)
const uint8 = new Uint8Array(buffer)

let atom = Atomics.add(uint8, 0, 2) // → 0

console.log(isAtomicsTag(atom.toString())) // → false
console.log(isAtomicsTag(Atomics.toString())) // → true
isBigIntTag() ⚡️
  • Checks if value is a default BigInt typetag
const { isBigIntTag, getTag } = require('typetags')

let bigint = BigInt(9007199254740991)
let typetag = getTag(bigint)

console.log(isBigIntTag(bigint.toString())) // → false
console.log(isBigIntTag(typetag)) // → true
isBigInt64ArrayTag() ⚡️
  • Checks if value is a default BigInt64Array typetag
const { isBigInt64ArrayTag, getTag } = require('typetags')

let bigint64 = new BigInt64Array(24)

console.log(isBigInt64ArrayTag(bigint64.toString())) // → false
console.log(isBigInt64ArrayTag(getTag(bigint64))) // → true
isBigUint64ArrayTag() ⚡️
  • Checks if value is a default BigUint64Array typetag
const { isBigUint64ArrayTag, getTag } = require('typetags')

let biguint = new BigUint64Array(24)

console.log(isBigUint64ArrayTag(biguint.toString())) // → false
console.log(isBigUint64ArrayTag(getTag(biguint))) // → true
isBooleanTag() ⚡️
  • Checks if value is a default Boolean typetag
const { isBooleanTag, getTag } = require('typetags')

let bool = true
let typetag = getTag(bool)

console.log(isBooleanTag(bool.toString())) // → false
console.log(isBooleanTag(typetag)) // → true
isConsoleTag() ⚡️
  • Checks if value is a default Console typetag
const { isConsoleTag, getTag } = require('typetags')

let consoleTypetag = getTag(console)

console.log(isConsoleTag(console.toString())) // → true
console.log(isConsoleTag(consoleTypetag)) // → true
isDataViewTag() ⚡️
  • Checks if value is a default DataView typetag
const { isDataViewTag } = require('typetags')

let buff = new SharedArrayBuffer(1024)
let view = new DataView(buff)

console.log(isDataViewTag(view.toString())) // → true
console.log(isDataViewTag('[object DataView]')) // → true
isDateTag() ⚡️
  • Checks if value is a default Date typetag
const { isDateTag, getTag } = require('typetags')

let today = new Date()
let typetag = getTag(today)

console.log(isDateTag(today.toString())) // → false
console.log(isDateTag(typetag)) // → true
isErrorTag() ⚡️
  • Checks if value is a default Error typetag
const { isErrorTag, getTag } = require('typetags')

let err = new Error('Bam')

console.log(isErrorTag(err.toString())) // → false
console.log(isErrorTag(getTag(err))) // → true
isEvalErrorTag() ⚡️
  • Checks if value is a default EvalError typetag
const { isEvalErrorTag } = require('typetags')

let err = new EvalError()

console.log(isEvalErrorTag(err.toString())) // → false
console.log(isEvalErrorTag(EvalError.toString())) // → false
isFinalizationRegistryTag() ⚡️
  • Checks if value is a default FinalizationRegistry typetag
const { isFinalizationRegistryTag, getTag } = require('typetags')

let final = new FinalizationRegistry((v) => {})
let typetag = getTag(final)

console.log(isFinalizationRegistryTag(final.toString())) // → true
console.log(isFinalizationRegistryTag(typetag)) // → true
isFloat32ArrayTag() ⚡️
  • Checks if value is a default Float32Array typetag
const { isFloat32ArrayTag, getTag } = require('typetags')

let float32 = new Float32Array()
let typetag = getTag(float32)

console.log(isFloat32ArrayTag(float32.toString())) // → false
console.log(isFloat32ArrayTag(typetag)) // → true
isFloat64ArrayTag() ⚡️
  • Checks if value is a default arguments typetag
const { isFloat64ArrayTag, getTag } = require('typetags')

let float64 = new Float64Array()

console.log(isFloat64ArrayTag(float64.toString())) // → false
console.log(isFloat64ArrayTag(getTag(float64))) // → true
isFunctionTag() ⚡️
  • Checks if value is a default Function typetag
const { isFunctionTag, getTag } = require('typetags')

let fn = () => 'hey!'
let typetag = getTag(fn)

console.log(isFunctionTag(fn.toString())) // → false
console.log(isFunctionTag(typetag)) // → true
isGeneratorTag() ⚡️
  • Checks if value is a default Generator typetag
const { isGeneratorTag } = require('typetags')

function* gene() {
  yield 1
}

let gen = gene()

console.log(isGeneratorTag(gen.toString())) // → true
console.log(isGeneratorTag(gene.toString())) // → false
isGeneratorFunctionTag() ⚡️
  • Checks if value is a default GeneratorFunction typetag
const { isGeneratorFunctionTag, getTag } = require('typetags')

function* gene() {
  yield 1
}

let typetag = getTag(gene)

console.log(isGeneratorFunctionTag(gene.toString())) // → false
console.log(isGeneratorFunctionTag(typetag)) // → true
isGlobalThisTag() ⚡️
  • Checks if value is a default globalThis typetag
const { isGlobalThisTag, getTag } = require('typetags')

let tag = getTag(globalThis)

console.log(isGlobalThisTag(tag)) // → true
console.log(isGlobalThisTag(process.toString())) // → false
isInfinityTag() ⚡️
  • Checks if value is a default Infinity typetag
const { isInfinityTag } = require('typetags')

let inf = 1 / 0

console.log(isInfinityTag(inf.toString())) // → true
console.log(isInfinityTag(Infinity.toString())) // → true
isInt8ArrayTag() ⚡️
  • Checks if value is a default Int8Array typetag
const { isInt8ArrayTag, getTag } = require('typetags')

let int8array = new Int8Array()
let tag = getTag(int8array)

console.log(isInt8ArrayTag(int8array.toString())) // → false
console.log(isInt8ArrayTag(tag)) // → true
isInt16ArrayTag() ⚡️
  • Checks if value is a default Int16Array typetag
const { isInt16ArrayTag } = require('typetags')

let int16array = new Int16Array()

console.log(isInt16ArrayTag(int16array.toString())) // → false
console.log(isInt16ArrayTag('[object Int16Array]')) // → true
isInt32ArrayTag() ⚡️
  • Checks if value is a default Int32Array typetag
const { isInt32ArrayTag, getTag } = require('typetags')

let int32array = new Int32Array()
let typetag = getTag(int32array)

console.log(isInt32ArrayTag(int32array.toString())) // → false
console.log(isInt32ArrayTag(typetag)) // → true
isIntlTag() ⚡️
  • Checks if value is a default Intl typetag
const { isIntlTag, TypeTags } = require('typetags')

console.log(isIntlTag(Intl.toString())) // → true
console.log(isIntlTag(TypeTags['Intl.Locale'])) // → true
isIntlCollatorTag() ⚡️
  • Checks if value is a default Intl.Collator typetag
const { isIntlCollatorTag } = require('typetags')

let coll = new Intl.Collator('en')

console.log(isIntlCollatorTag(coll.toString())) // → true
console.log(isIntlCollatorTag(Intl.toString())) // → false
isIntlDateTimeFormatTag() ⚡️
  • Checks if value is a default Intl.DateTimeFormat typetag
const { isIntlDateTimeFormatTag } = require('typetags')

let date = new Intl.DateTimeFormat('en')

console.log(isIntlDateTimeFormatTag(date.toString())) // → true
console.log(isIntlDateTimeFormatTag('[object Intl.DateTimeFormat]')) // → true
isIntlListFormatTag() ⚡️
  • Checks if value is a default Intl.ListFormat typetag
const { isIntlListFormatTag, TypeTags } = require('typetags')

let list = new Intl.ListFormat('en')
let tag = TypeTags['Intl.ListFormat']

console.log(isIntlListFormatTag(list.toString())) // → true
console.log(isIntlListFormatTag(tag)) // → true
isIntlLocaleTag() ⚡️
  • Checks if value is a default Intl.Locale typetag
const { isIntlLocaleTag, getTag } = require('typetags')

let locale = new Intl.Locale('de') // locale.toString() → 'de'
let typetag = getTag(locale)

console.log(isIntlLocaleTag(locale.toString())) // → false
console.log(isIntlLocaleTag(typetag)) // → true
isIntlNumberFormatTag() ⚡️
  • Checks if value is a default Intl.NumberFormat typetag
const { isIntlNumberFormatTag, TypeTags } = require('typetags')

let num = new Intl.NumberFormat('en')
let tag = TypeTags['Intl.NumberFormat']

console.log(isIntlNumberFormatTag(num.toString())) // → true
console.log(isIntlNumberFormatTag(tag)) // → true
isIntlPluralRulesTag() ⚡️
  • Checks if value is a default Intl.PluralRules typetag
const { isIntlPluralRulesTag, getTag } = require('typetags')

let rules = new Intl.PluralRules('en')
let typetag = getTag(rules)

console.log(isIntlPluralRulesTag(typetag)) // → true
console.log(isIntlPluralRulesTag(rules.toString())) // → true
isIntlRelativeTimeFormatTag() ⚡️
  • Checks if value is a default Intl.RelativeTimeFormat typetag
const { isIntlRelativeTimeFormatTag } = require('typetags')

let intl = new Intl.RelativeTimeFormat('en')

console.log(isIntlRelativeTimeFormatTag(intl.toString())) // → true
console.log(isIntlRelativeTimeFormatTag('DD mm')) // → false
isIteratorTag() ⚡️
  • Checks if value is a default <type> Iterator typetag
const { isIteratorTag, getTag } = require('typetags')

let iterator = ['Array'][Symbol.iterator]()

console.log(isIteratorTag(getTag(iterator))) // → true
console.log(isIteratorTag(iterator.toString())) // → true
isJsonTag() ⚡️
  • Checks if value is a default JSON typetag
const { isJsonTag } = require('typetags')

console.log(isJsonTag(JSON.toString())) // → true
console.log(isJsonTag('{"foo":"bar"}')) // → false
isMapTag() ⚡️
  • Checks if value is a default Map typetag
const { isMapTag } = require('typetags')

let map = new Map([[1, 2]])

console.log(isMapTag(map.toString())) // → true
console.log(isMapTag('[object WeakMap]')) // → false
isMapIteratorTag() ⚡️
  • Checks if value is a default Map Iterator typetag
const { isMapIteratorTag, getTag } = require('typetags')

let map = new Map([[1, 2]])
let tag = getTag(map.values())

console.log(isMapIteratorTag(tag)) // → true
console.log(isMapIteratorTag(map.toString())) // → false
isMathTag() ⚡️
  • Checks if value is a default Math typetag
const { isMathTag } = require('typetags')

let number = Math.random()

console.log(isMathTag(number.toString())) // → false
console.log(isMathTag(Math.toString())) // → true
isNaNTag() ⚡️
  • Checks if value is a default NaN typetag
const { isNaNTag, TypeTags } = require('typetags')

let str = NaN.toString() // → 'NaN'
let tag = TypeTags.NaN // → '[object Number]'

console.log(isNaNTag(str)) // → true
console.log(isNaNTag(tag)) // → true
isNullTag() ⚡️
  • Checks if value is a default Null typetag
const { isNullTag, getTag } = require('typetags')

let nu = null

console.log(isNullTag(null)) // → false
console.log(isNullTag(getTag(nu))) // → true
isNumberTag() ⚡️
  • Checks if value is a default Number typetag
const { isNumberTag, getTag } = require('typetags')

let num = 1
let typetag = getTag(num)

console.log(isNumberTag(num.toString())) // → false
console.log(isNumberTag(typetag)) // → true
isObjectTag() ⚡️
  • Checks if value is a default Object typetag
const { isObjectTag, TypeTags } = require('typetags')

let o = { name: 'typetags' }
let tag = TypeTags.Object

console.log(isObjectTag(tag)) // → true
console.log(isObjectTag(o.toString())) // → true
isProcessTag() ⚡️
  • Checks if value is a default process typetag
const { isProcessTag, getTag } = require('typetags')

let processTypetag = getTag(process)

console.log(isProcessTag(processTypetag)) // → true
console.log(isProcessTag(process.toString())) // → true
isPromiseTag() ⚡️
  • Checks if value is a default Promise typetag
const { isPromiseTag } = require('typetags')

let getUser = new Promise((r) => r)
let bytes = new Uint8Array([0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00])
let wtf = WebAssembly.instantiate(bytes) // magic Promise

console.log(isPromiseTag(wtf.toString())) // → true
console.log(isPromiseTag(getUser.toString())) // → true
isRangeErrorTag() ⚡️
  • Checks if value is a default RangeError typetag
const { isRangeErrorTag, TypeTags } = require('typetags')

let err = new RangeError('bam')

console.log(isRangeErrorTag(err.toString())) // → false
console.log(isRangeErrorTag(TypeTags.RangeError)) // → true
console.log(isRangeErrorTag('[object RangeError]')) // → false
isReferenceErrorTag() ⚡️
  • Checks if value is a default ReferenceError typetag
const { isReferenceErrorTag, getTag } = require('typetags')

let err = new ReferenceError('oops')
let errorTypetag = getTag(err)

console.log(isReferenceErrorTag(err.toString())) // → false
console.log(isReferenceErrorTag(errorTypetag)) // → true
isReflectTag() ⚡️
  • Checks if value is a default Reflect typetag
const { isReflectTag, getTag } = require('typetags')

let reflectTag = getTag(Reflect)

console.log(isReflectTag(reflectTag)) // → true
console.log(isReflectTag(Reflect.toString())) // → true
isRegExpTag() ⚡️
  • Checks if value is a default RegExp typetag
const { isRegExpTag } = require('typetags')

let regex = new RegExp('')
let typetag = getTag(regex)

console.log(isRegExpTag(regex.toString())) // → false
console.log(isRegExpTag(typetag)) // → true
isSetTag() ⚡️
  • Checks if value is a default Set typetag
const { isSetTag } = require('typetags')

let mySet = new Set([1])

console.log(isSetTag('[object Set]')) // → true
console.log(isSetTag(mySet.toString())) // → true
isSetIteratorTag() ⚡️
  • Checks if value is a default Set Iterator typetag
const { isSetIteratorTag, getTag } = require('typetags')

let s = new Set([1])
let iteratorTag = getTag(s.values())

console.log(isSetIteratorTag(s.toString())) // → false
console.log(isSetIteratorTag(iteratorTag)) // → true
isSharedArrayBufferTag() ⚡️
  • Checks if value is a default SharedArrayBuffer typetag
const { isSharedArrayBufferTag } = require('typetags')

let arr = new SharedArrayBuffer(1024)

console.log(isSharedArrayBufferTag(arr.toString())) // → true
console.log(isSharedArrayBufferTag('[object Array]')) // → false
isStringTag() ⚡️
  • Checks if value is a default String typetag
const { isStringTag } = require('typetags')

let str = 'hey'

console.log(isStringTag(str.toString())) // → false
console.log(isStringTag('[object String]')) // → true
isStringIteratorTag() ⚡️
  • Checks if value is a default String Iterator typetag
const { isStringIteratorTag, getTag } = require('typetags')

let iterator = ''[Symbol.iterator]()

console.log(isStringIteratorTag(iterator.toString()) // → true
console.log(isStringIteratorTag(getTag(iterator))) // → true
isSymbolTag() ⚡️
  • Checks if value is a default Symbol typetag
const { isSymbolTag, getTag } = require('typetags')

let sym = Symbol('1')
let tag = getTag(sym)

console.log(isSymbolTag(tag)) // → true
console.log(isSymbolTag(sym.toString())) // → false
isSyntaxErrorTag() ⚡️
  • Checks if value is a default SyntaxError typetag
const { isSyntaxErrorTag } = require('typetags')

let err = new SyntaxError()

console.log(isSyntaxErrorTag(err.toString())) // → false
console.log(isSyntaxErrorTag('[object Error]')) // → true
isTextDecoderTag() ⚡️
  • Checks if value is a default TextDecoder typetag
const { isTextDecoderTag, getTag } = require('typetags')

let decoder = new TextDecoder()
let tag = decoder.toString()

console.log(isTextDecoderTag(tag)) // → true
console.log(isTextDecoderTag(getTag(decoder))) // → true
isTextEncoderTag() ⚡️
  • Checks if value is a default TextEncoder typetag
const { isTextEncoderTag, getTag } = require('typetags')

let encoder = new TextEncoder()
let tag = getTag(encoder)

console.log(isTextEncoderTag(tag)) // → true
console.log(isTextEncoderTag(encoder.toString())) // → true
isTypedArrayTag() ⚡️
  • Checks if value is a default TypedArray typetag
const { isTypedArrayTag, TypeTags } = require('typetags')

let typedArray = new Int8Array(16))

console.log(isTypedArrayTag(typedArray.toString())) // → false
console.log(isTypedArrayTag(TypeTag.Float32Array)) // → true
isTypeErrorTag() ⚡️
  • Checks if value is a default TypeError typetag
const { isTypeErrorTag, getTag } = require('typetags')

let err = new TypeError()

console.log(isTypeErrorTag(getTag(err))) // → true
console.log(isTypeErrorTag(err.toString())) // → false
isUint8ArrayTag() ⚡️
  • Checks if value is a default Uint8Array typetag
const { isUint8ArrayTag, getTag } = require('typetags')

let uint = new Uint8Array()

console.log(isUint8ArrayTag(uint.toString())) // → false
console.log(isUint8ArrayTag(getTag(uint))) // → true
isUint8ClampedArrayTag() ⚡️
  • Checks if value is a default Uint8ClampedArray typetag
const { isUint8ClampedArrayTag, getTag } = require('typetags')

let clamped = new Uint8ClampedArray()

console.log(isUint8ClampedArrayTag(clamped.toString())) // → false
console.log(isUint8ClampedArrayTag(getTag(clamped))) // → true
isUint16ArrayTag() ⚡️
  • Checks if value is a default Uint16Array typetag
const { isUint16ArrayTag } = require('typetags')

let uint = new Uint16Array()

console.log(isUint16ArrayTag(uint.toString())) // → false
console.log(isUint16ArrayTag('[object Uint16Array]')) // → true
isUint32ArrayTag() ⚡️
  • Checks if value is a default Uint32Array typetag
const { isUint32ArrayTag } = require('typetags')

let uint = new Uint32Array()

console.log(isUint32ArrayTag(uint.toString())) // → false
console.log(isUint32ArrayTag('[object Uint32Array]')) // → true
isUndefinedTag() ⚡️
  • Checks if value is a default Undefined typetag
const { isUndefinedTag } = require('typetags')

let nada = undefined
let tag = getTag(nada) // → [object Undefined]

console.log(isUndefinedTag(hey.toString())) // → TypeError
console.log(isUndefinedTag(tag)) // → true
isURIErrorTag() ⚡️
  • Checks if value is a default URIError typetag
const { isURIErrorTag } = require('typetags')

console.log(isURIErrorTag('[object Error]')) // → true
console.log(isURIErrorTag(URIError.toString())) // → false
isURLTag() ⚡️
  • Checks if value is a default URL typetag
const { isURLTag, getTag } = require('typetags')

let url = new URL('https://npmjs.com/typetags') // → prints 'https://npmjs.com/typetags'

console.log(isURLTag(url.toString())) // → false
console.log(isURLTag(getTag(url))) // → true
isURLSearchParamsTag() ⚡️
  • Checks if value is a default URLSearchParams typetag
const { isURLSearchParamsTag, getTag } = require('typetags')

let params = new URLSearchParams('id') // .toString() → 'id='

console.log(isURLSearchParamsTag(params.toString())) // → false
console.log(isURLSearchParamsTag(getTag(params))) // → true
isWeakMapTag() ⚡️
  • Checks if value is a default WeakMap typetag
const { isWeakMapTag, getTag } = require('typetags')

let weakmap = new WeakMap()
let tag = getTag(weakmap)

console.log(isWeakMapTag(weakmap.toString())) // → false
console.log(isWeakMapTag(tag)) // → true
isWeakRefTag() ⚡️
  • Checks if value is a default WeakRef typetag
const { isWeakRefTag } = require('typetags')

let weakref = new WeakRef({})
let tag = getTag(weakref)

console.log(isWeakRefTag(weakref.toString())) // → false
console.log(isWeakRefTag(tag)) // → true
isWeakSetTag() ⚡️
  • Checks if value is a default WeakSet typetag
const { isWeakSetTag } = require('typetags')

let weakset = new WeakSet()

console.log(isWeakSetTag(weakset.toString())) // → true
console.log(isWeakSetTag('[object WeakSet]')) // → true
isWasmTag() ⚡️
  • Checks if value is a default WebAssembly typetag
const { isWebAssemblyTag, TypeTags } = require('typetags')

let wasm = new WebAssembly.Table({ initial: 1, element: 'anyfunc' })

console.log(isWebAssemblyTag(wasm.toString())) // → true
console.log(isWebAssemblyTag(TypeTags['WebAssembly.Module'])) // → true
isWasmModuleTag() ⚡️
  • Checks if value is a default WebAssembly.Module typetag
const { isWasmModuleTag } = require('typetags')

let bytes = new Uint8Array([0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00])
let wsmod = new WebAssembly.Module(bytes)

console.log(isWasmModuleTag(wsmod.toString())) // → true
console.log(isWasmModuleTag(bytes.toString())) // → false
isWasmGlobalTag() ⚡️
  • Checks if value is a default WebAssembly.Global typetag
const { isWasmGlobalTag } = require('typetags')

let wg = new WebAssembly.Global({ value: 'i32', mutable: true }, 0)

console.log(isWasmGlobalTag(wg.toString())) // → true
console.log(isWasmGlobalTag('[object WebAssembly.Global]')) // → true
isWasmInstanceTag() ⚡️
  • Checks if value is a default WebAssembly.Instance typetag
const { isWasmInstanceTag, TypeTags } = require('typetags')

let bytes = new Uint8Array([0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00])
let mod = new WebAssembly.Module(bytes)
let instance = new WebAssembly.Instance(mod, {})

console.log(isWasmInstanceTag(instance.toString())) // → true
console.log(isWasmInstanceTag(TypeTags.WebAssembly)) // → false
isWasmMemoryTag() ⚡️
  • Checks if value is a default WebAssembly.Memory typetag
const { isWasmMemoryTag } = require('typetags')

let memo = new WebAssembly.Memory({ initial: 1, max: 10 })

console.log(isWasmMemoryTag(memo.toString())) // → true
console.log(isWasmMemoryTag('[object WebAssembly]')) // → false
isWasmTableTag() ⚡️
  • Checks if value is a default WebAssembly.Table typetag
const { isWasmTableTag, getTag } = require('typetags')

let table = new WebAssembly.Table({ initial: 1, element: 'anyfunc' })
let typetag = getTag(table)

console.log(isWasmTableTag(typetag)) // → true
console.log(isWasmTableTag(table.toString())) // → true
isWasmCompileErrorTag() ⚡️
  • Checks if value is a default WebAssembly.CompileError typetag
const { isWasmCompileErrorTag, TypeTags } = require('typetags')

let tag = TypeTags['WebAssembly.CompileError']

console.log(isWasmCompileErrorTag(tag)) // → true
console.log(isWasmCompileErrorTag('[object Error]')) // → true
isWasmLinkErrorTag() ⚡️
  • Checks if value is a default WebAssembly.LinkError typetag
const { isWasmLinkErrorTag, getTag } = require('typetags')

let err = new WebAssembly.LinkError('123')
// err.toString() => LinkError: 123
let typetag = getTag(err)

console.log(isWasmLinkErrorTag(err.toString())) // → false
console.log(isWasmLinkErrorTag(typetag)) // → true
isWasmRuntimeErrorTag() ⚡️
  • Checks if value is a default WebAssembly.RuntimeError typetag
const { isWasmRuntimeErrorTag, getTag } = require('typetags')

let err = new WebAssembly.RuntimeError()
// err.toString() => [object Error]

console.log(isWasmRuntimeErrorTag(err.toString())) // → true
console.log(isWasmRuntimeErrorTag(getTag(err))) // → true
isWindowTag() ⚡️
  • Checks if value is a default Window typetag
const { isWindowTag, getTag } = require('typetags')

let tag = globalThis.toString() // depends on environment
let typetag = getTag(globalThis)

console.log(isWindowTag(tag)) // → false
console.log(isWindowTag(typetag)) // → true
isWorkerTag() ⚡️
  • Checks if value is a default Worker typetag
const { isWorkerTag } = require('typetags')

console.log(isWorkerTag(process.toString())) // → false
console.log(isWorkerTag('[object Worker]')) // → true

Helpers

hasDefaultTag() ⚡️
  • Checks if the received data type has a native default tag
import { hasDefaultTag } from 'typetags'

function User(name) {
  this.name = name
}

User.prototype.toString = function () {
  return `${this.name}`
}

const jack = new User('Jack')

console.log(hasDefaultTag(jack)) // → false
console.log(hasDefaultTag([1, 2, 3])) // → true

See typetags wiki for more info

Tests

jest --coverage

---------------|---------|----------|---------|---------|-------------------
File           | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
---------------|---------|----------|---------|---------|-------------------
All files      |     100 |      100 |     100 |     100 |
 get-tag.js    |     100 |      100 |     100 |     100 |
 predicates.js |     100 |      100 |     100 |     100 |
 type-tags.js  |     100 |      100 |     100 |     100 |
---------------|---------|----------|---------|---------|-------------------

Test Suites: 3 passed, 3 total
Tests:       2 skipped, 323 passed, 325 total
Snapshots:   0 total
Time:        1.571 s, estimated 2 s
Ran all test suites.
✨  Done in 2.40s.

TypeScript

Using TypeScript? We've got you covered. The package comes with d.ts declaration files.

⚡️ Powered by Moka Tecnologia — < > with lots of ☕️ by Moa Torres