Analytics
/

Type utils

Utility library for runtime type checking

A tiny tree shakable utility library for runtime type checking in 2.3kb.

This library will work with analytics or as a standalone package.

See live demo.

Exposes 60 re-usable functions and environment flags for runtime type checking.

Why this package?

This package exposes re-usable runtime type checking functions. This is useful for shrinking bundle sizes.

How to install

Install @analytics/type-utils from npm.

npm install @analytics/type-utils

API

Below is the api for @analytics/type-utils.

isProd

Boolean flag, true when process.env.NODE_ENV is 'production'.

import { isProd } from '@analytics/type-utils'

if (isProd) {
  console.log('do things in production env')
}

isStaging

Boolean flag, true when process.env.NODE_ENV is 'staging'.

import { isStaging } from '@analytics/type-utils'

if (isStaging) {
  console.log('do things in staging env')
}

isDev

Boolean flag, true when process.env.NODE_ENV is 'development'.

import { isDev } from '@analytics/type-utils'

if (isDev) {
  console.log('do things in development env')
}

isBrowser

Boolean flag, true when running in a browser context (document is defined).

import { isBrowser } from '@analytics/type-utils'

if (isBrowser) {
  console.log('do things in browser env')
}

isLocalHost

Boolean flag, true when in a browser and window.location.hostname is 'localhost'.

import { isLocalHost } from '@analytics/type-utils'

if (isLocalHost) {
  console.log('running on localhost')
}

isNode

Boolean flag, true when running in a Node.js context.

import { isNode } from '@analytics/type-utils'

if (isNode) {
  console.log('do things in node env')
}

isDeno

Boolean flag, true when running in a Deno context.

import { isDeno } from '@analytics/type-utils'

if (isDeno) {
  console.log('do things in deno env')
}

isWebWorker

Boolean flag, true when running in a WebWorker context.

import { isWebWorker } from '@analytics/type-utils'

if (isWebWorker) {
  console.log('do things in webworker env')
}

isJsDom

Boolean flag, true when running in a JSDOM context.

import { isJsDom } from '@analytics/type-utils'

if (isJsDom) {
  console.log('do things in JSDOM env')
}

getTypeName

Returns the capitalized type name of a value.

import { getTypeName } from '@analytics/type-utils'

getTypeName([]) // 'Array'
getTypeName(null) // 'Null'

getType

Returns the type of a value, lowercased by default. Pass false to keep the capitalized name.

import { getType } from '@analytics/type-utils'

getType([]) // 'array'
getType(new Date()) // 'date'
getType([], false) // 'Array'

ctorName

Returns the constructor name of a value, or null if it has no function constructor.

import { ctorName } from '@analytics/type-utils'

ctorName(new Date()) // 'Date'
ctorName([]) // 'Array'

isFunction

Check if value is a function.

import { isFunction } from '@analytics/type-utils'

function xyz() {}
isFunction(xyz) // true

isString

Check if value is a string.

import { isString } from '@analytics/type-utils'

isString('hi') // true

isUndefined

Check if value is undefined.

import { isUndefined } from '@analytics/type-utils'

let myVal
isUndefined(myVal) // true

isDefined

Check if value is not undefined.

import { isDefined } from '@analytics/type-utils'

isDefined('hi') // true
isDefined(undefined) // false

isBoolean

Check if value is a boolean.

import { isBoolean } from '@analytics/type-utils'

isBoolean(true) // true

isSymbol

Check if value is a symbol.

import { isSymbol } from '@analytics/type-utils'

isSymbol(Symbol('x')) // true

isNull

Check if value is null.

import { isNull } from '@analytics/type-utils'

isNull(null) // true

isNumber

Check if value is a number. Returns false for NaN.

import { isNumber } from '@analytics/type-utils'

isNumber(123) // true
isNumber(NaN) // false
isNumber(Infinity) // true

isNumberLike

Check if value can be parsed as a number.

import { isNumberLike } from '@analytics/type-utils'

isNumberLike('1.1') // true
isNumberLike('abc') // false

isClass

Check if value is a javascript class.

import { isClass } from '@analytics/type-utils'

class MyClass {}
isClass(MyClass) // true

isArray

Check if value is an array.

import { isArray } from '@analytics/type-utils'

isArray(['x', 'y']) // true

isObject

Check if value is a plain object.

import { isObject } from '@analytics/type-utils'

isObject({ cool: 'hello' }) // true
isObject([]) // false

isObjectLike

Check if value is object-like (truthy and typeof object).

import { isObjectLike } from '@analytics/type-utils'

isObjectLike({}) // true
isObjectLike(null) // false

isJson

Check if value is a parsable JSON string.

import { isJson } from '@analytics/type-utils'

isJson('{"a":5}') // true
isJson('[]') // true
isJson('{a":5}') // false

isPrimitive

Check if value is a primitive scalar value.

import { isPrimitive } from '@analytics/type-utils'

isPrimitive(true) // true
isPrimitive(0) // true
isPrimitive(null) // true
isPrimitive({}) // false
isPrimitive(function() {}) // false

isMethod

Check if an object has a function at the given property name.

import { isMethod } from '@analytics/type-utils'

const obj = { key: () => {}, keyTwo: 'foobar' }
isMethod(obj, 'key') // true
isMethod(obj, 'keyTwo') // false

isPromise

Check if value is a Promise.

import { isPromise } from '@analytics/type-utils'

isPromise(Promise.resolve()) // true

isGenerator

Check if value is a generator.

import { isGenerator } from '@analytics/type-utils'

function* gen() { yield 1 }
isGenerator(gen()) // true

isGeneratorFunction

Check if value is a generator function.

import { isGeneratorFunction } from '@analytics/type-utils'

isGeneratorFunction(function* () {}) // true
isGeneratorFunction(() => {}) // false

isAsyncFunction

Check if value is an async function.

import { isAsyncFunction } from '@analytics/type-utils'

isAsyncFunction(async () => {}) // true
isAsyncFunction(() => {}) // false

isSet

Check if value is a Set.

import { isSet } from '@analytics/type-utils'

isSet(new Set()) // true

isMap

Check if value is a Map.

import { isMap } from '@analytics/type-utils'

isMap(new Map()) // true

isRegex

Check if value is a regular expression.

import { isRegex } from '@analytics/type-utils'

isRegex(/pattern/gm) // true

isBuffer

Check if value is a Buffer.

import { isBuffer } from '@analytics/type-utils'

isBuffer(Buffer.from('x')) // true

isError

Check if value is an Error.

import { isError } from '@analytics/type-utils'

isError(new Error()) // true

isErrorLike

Check if value has string name and message properties.

import { isErrorLike } from '@analytics/type-utils'

isErrorLike(new Error()) // true
isErrorLike({ name: 'Error!', message: 'This is an error' }) // true
isErrorLike({}) // false

isTypeError

Check if value is a TypeError.

import { isTypeError } from '@analytics/type-utils'

isTypeError(new TypeError()) // true
isTypeError(new Error()) // false

isSyntaxError

Check if value is a SyntaxError.

import { isSyntaxError } from '@analytics/type-utils'

isSyntaxError(new SyntaxError()) // true
isSyntaxError(new Error()) // false

isNoOp

Check if a function is a no-op (empty body).

import { isNoOp } from '@analytics/type-utils'

isNoOp(() => {}) // true
isNoOp(() => { console.log('hi') }) // false

isArguments

Check if value is a function arguments object.

import { isArguments } from '@analytics/type-utils'

function fn() { return isArguments(arguments) }
fn() // true
isArguments([]) // false

isTruthy

Check if value is truthy. The string 'false' is treated as false.

import { isTruthy } from '@analytics/type-utils'

isTruthy('true') // true
isTruthy(1) // true
isTruthy('false') // false
isTruthy(0) // false

isFalsy

Check if value is falsy.

import { isFalsy } from '@analytics/type-utils'

isFalsy(false) // true
isFalsy(null) // true
isFalsy('') // true
isFalsy([]) // false

isTrue

Check if value is exactly true.

import { isTrue } from '@analytics/type-utils'

isTrue(true) // true
isTrue(1) // false

isFalse

Check if value is exactly false.

import { isFalse } from '@analytics/type-utils'

isFalse(false) // true
isFalse(0) // false

isEmail

Check if value is an email address.

import { isEmail } from '@analytics/type-utils'

isEmail('email@email.com') // true
isEmail('other-thing') // false

isDate

Check if value is a Date.

import { isDate } from '@analytics/type-utils'

isDate(new Date()) // true
isDate('2022-01-02') // false

isIsoDate

Check if value is an ISO date string.

import { isIsoDate } from '@analytics/type-utils'

isIsoDate('2022-01-02T06:45:28.547Z') // true
isIsoDate('2022-01-02') // false

isEmpty

Check if value is empty (null, or an empty array, set, map, or object).

import { isEmpty } from '@analytics/type-utils'

isEmpty(null) // true
isEmpty([]) // true
isEmpty([1, 2, 3]) // false
isEmpty({ a: 1 }) // false

isNodeList

Check if value is a list of DOM nodes.

import { isNodeList } from '@analytics/type-utils'

const buttons = document.querySelectorAll('button')
isNodeList(buttons) // true

isElement

Check if value is a DOM element. Pass an optional node type to also match the element type.

import { isElement } from '@analytics/type-utils'

const formElement = document.querySelector('.my-form')
isElement(formElement) // true
isElement(formElement, 'form') // true

isNodeType

Check if a DOM element matches a given node name.

import { isNodeType } from '@analytics/type-utils'

const input = document.querySelector('input')
isNodeType(input, 'input') // true

isForm

Check if value is a <form> element.

import { isForm } from '@analytics/type-utils'

const formElement = document.querySelector('.my-form')
isForm(formElement) // true

isButton

Check if value is a <button> element.

import { isButton } from '@analytics/type-utils'

const btn = document.querySelector('.my-button')
isButton(btn) // true

isInput

Check if value is an <input> element.

import { isInput } from '@analytics/type-utils'

const input = document.querySelector('.my-input')
isInput(input) // true

isSelect

Check if value is a <select> element.

import { isSelect } from '@analytics/type-utils'

const select = document.querySelector('.my-select')
isSelect(select) // true

isHidden

Check if a DOM element is hidden.

import { isHidden } from '@analytics/type-utils'

const el = document.querySelector('.my-el')
isHidden(el) // true

noOp

A no-op function that does nothing.

import { noOp } from '@analytics/type-utils'

const callback = options.callback || noOp
callback()

ensureArray

Wrap a value in an array if it is not already one.

import { ensureArray } from '@analytics/type-utils'

ensureArray('x') // ['x']
ensureArray(['x', 'y']) // ['x', 'y']
ensureArray() // []

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