checker.js

A set of boilerplate utilities for checking any type of values ​​without headaches or common mistakes

Installation

With pnpm

pnpm install @nawael/checker.js --save

With npm

npm install @nawael/checker.js --save

With yarn

yarn add @nawael/checker.js --save

Integration

For CommonJS

const { isArray, isString, isNumber, ... } = require('@nawael/checker.js')

For ESM

import { isArray, isString, isNumber, ... } from '@nawael/checker.js'

Usage examples

Works with Object

// instead of using typeof
if (typeof arg === 'object') {
  // ...some stuff
  // But if we do Object.keys(arg) we throw an error if arg is null! 😱
  // TypeError: Cannot convert undefined or null to object
}

// use isObject
import { isObject } from '@nawael/checker.js'

isObject(arg)
// ✅ true if arg = {}
// ❌ false if arg = null cause typeof null === 'object'
// ❌ false if arg = [] cause typeof [] === 'object'

Works with Number

// instead of using typeof
if (typeof arg === 'number') {
  // some stuff
}

// use isNumber
import { isNumber } from '@nawael/checker.js'

isNumber(arg)
// ✅ true if arg = 0 or arg = Infinity or -Infinity or
// ✅ true if arg = new Number() cause typeof new Number() === 'object'
// ❌ false if arg = NaN cause NaN is a number and we need to avoid NaN
// 😱 so we must check Object.prototype.toString.call(arg) === '[object Number]'

Standalone "is" API

[!TIP] All APIs are available in the standalone "is" API

// instead of importing all API
import { isArray, isString, isNumber, ... } from '@nawael/checker.js'

// use "is" API and avoid boring imports
import { is } from '@nawael/checker.js'

is.array(arg) // isArray(arg)
is.string(arg) // isString(arg)
is.number(arg) // isNumber(arg)

// ...and so on

Available APIs

primitive checker

APIs	standalone is
isBoolean(arg)	is.boolean(arg)
isBooleanOrNull(arg)	is.booleanOrNull(arg)
isBigInt(arg)	is.bigInt(arg)
isNumber(arg)	is.number(arg)
isNull(arg)	is.null(arg)
isString(arg)	is.string(arg)
isUndefined(arg)	is.undefined(arg)
isSymbol(arg)	is.symbol(arg)
isPrimitive(arg)	is.primitive(arg)

String checker

APIs	standalone is
isStringOrNull(arg)	is.string.orNull(arg)
isStringEmpty(arg)	is.string.empty(arg)
isStringNotEmpty(arg)	is.string.notEmpty(arg)
isAlpha(arg)	is.string.alpha(arg)
isNumeric(arg)	is.string.numeric(arg)
isAlphanumeric(arg)	is.string.alphanumeric(arg)
isEmail(arg)	is.string.email(arg)
isUrl(arg)	is.string.url(arg)
isBinaryString(arg)	is.string.binary(arg)
isBase64(arg)	is.string.base64(arg)

Number checker

APIs	standalone is
isPositiveNumber(arg)	is.number.positive(arg)
isNegativeNumber(arg)	is.number.negative(arg)
isInfinite(arg)	is.number.infinite(arg)
isOdd(arg)	is.number.odd(arg)
isEven(arg)	is.number.even(arg)
isNumberOrNull(arg)	is.number.orNull(arg)
isDecimal(arg)	is.number.decimal(arg)
isGreaterThan(arg, compare)	is.number.greaterThan(arg, compare)
isGreaterEqualThan(arg, compare)	is.number.greaterEqualThan(arg, compare)
isLessThan(arg, compare)	is.number.lessThan(arg, compare)
isLessEqualThan(arg, compare)	is.number.lessEqualThan(arg, compare)
isBetween(arg, start, finish)	is.number.between(arg, start, finish)
isBetweenEqual(arg, start, finish)	is.number.betweenEqual(arg, start, finish)

Object checker

APIs	standalone is
isObject(arg)	is.object(arg)
isObjectOrNull(arg)	is.object.orNull(arg)
isObjectNotEmpty(arg)	is.object.notEmpty(arg)
isObjectEmpty(arg)	is.object.empty(arg)

Array checker

APIs	standalone is
isArray(arg)	is.array(arg)
isMap(arg)	is.map(arg)
isSet(arg)	is.set(arg)
isArrayOrNull(arg)	is.array.orNull(arg)
isArrayOfNumbers(arg)	is.array.number(arg)
isArrayOfStrings(arg)	is.array.string(arg)
isArrayOfObjects(arg)	is.array.object(arg)
isArrayOfBooleans(arg)	is.array.boolean(arg)
isArrayNotEmpty(arg)	is.array.notEmpty(arg)
isArrayEmpty(arg)	is.array.empty(arg)

Function checker

APIs	standalone is
isFunction(arg)	is.function(arg)
isAsyncFunction(arg)	is.async(arg)
isGeneratorFunction(arg)	is.generator(arg)

Promise checker

APIs	standalone is
isPromise(arg)	is.promise(arg)
isFullfilledPromise(arg)	is.promise.fullfilled(arg)
isRejectedPromise(arg)	is.promise.rejected(arg)
isPendingPromise(arg)	is.promise.pending(arg)

Misc checker

APIs	standalone is
isDate(arg)	is.date(arg)
isRegExp(arg)	is.regExp(arg)
isError(arg)	is.error(arg)
isFalsy(arg)	is.falsy(arg)
isTruthy(arg)	is.truthy(arg)

UUID checker

APIs	standalone is
isUUID(arg)	is.uuid(arg)
isUUIDv3(arg)	is.uuidv3(arg)
isUUIDv4(arg)	is.uuidv4(arg)
isUUIDv5(arg)	is.uuidv5(arg)

Environment checker

APIs	standalone is
isWindow()	is.window()
isNode()	is.node()
isBrowser()	is.browser()
isJsDom()	is.jsDom()
isWebWorker()	is.webWorker()
isBun()	is.bun()
isMac()	is.mac()
isLinux()	is.linux()
isWindows()	is.windows()

Platform checker

APIs	standalone is
isIpad()	is.ipad()
isIphone()	is.iphone()
isIpod()	is.ipod()
isAndroid()	is.android()
isAndroidPhone()	is.androidPhone()
isAndroidTablet()	is.androidTablet()
isMobile()	is.mobile()
isTablet()	is.tablet()
isDesktop()	is.desktop()
isIos()	is.ios()

Browser checker

APIs	standalone is
isChrome()	is.chrome()
isFirefox()	is.firefox()
isOpera()	is.opera()
isOperaMini()	is.operaMini()
isSafari()	is.safari()
isEdge()	is.edge()
isIe()	is.ie()

IP checker

APIs	standalone is
isIPv4(arg)	is.ipv4(arg)
isIPv6(arg)	is.ipv6(arg)
isIP(arg)	is.ip(arg)