is

Small utility package that provides a set of functions to check if a given argument is of a certain type

Functions

detect

Returns the type of given value.

import { detect } from '@plq/is'

console.log(detect('')) // Output: 'string'
console.log(detect(1)) // Output: 'number'
console.log(detect(true)) // Output: 'boolean'
console.log(detect({})) // Output: 'object'
console.log(detect([])) // Output: 'array'

getTag

Returns the tag of given value.

import { getTag } from '@plq/is'

console.log(getTag('')) // Output: '[object String]'
console.log(getTag(1)) // Output: '[object Number]'
console.log(getTag(true)) // Output: '[object Boolean]'
console.log(getTag({})) // Output: '[object Object]'
console.log(getTag([])) // Output: '[object Array]'

isFunction

Checks if a given value is a function.

import { isFunction } from '@plq/is'

console.log(isFunction(() => {})) // Output: true
console.log(isFunction({})) // Output: false
console.log(isFunction(async () => {})) // Output: false

isAsyncFunction

Checks if a given value is an asynchronous function.

javascript
import { isAsyncFunction } from '@plq/is'

console.log(isAsyncFunction(async () => {})) // Output: true
console.log(isAsyncFunction(() => {})) // Output: false

isGeneratorFunction

Checks if a given value is a generator function.

import { isGeneratorFunction } from '@plq/is'

console.log(isGeneratorFunction(function* () {})) // Output: true
console.log(isGeneratorFunction(() => {})) // Output: false

isPromise

Checks if a given value is a Promise.

import { isPromise } from '@plq/is'

console.log(isPromise(Promise.resolve())) // Output: true
console.log(isPromise(async () => {})) // Output: false

isPromiseLike

Checks if a given value is a Promise-like.

import { isPromiseLike } from '@plq/is'

console.log(isPromiseLike(Promise.resolve())) // Output: true
console.log(isPromiseLike({ then: () => {} })) // Output: true
console.log(isPromiseLike(async () => {})) // Output: false

isArray

Checks if a given value is an array.

import { isArray } from '@plq/is'

console.log(isArray([])) // Output: true
console.log(isArray({})) // Output: false

isArrayOf

Checks if a given value is an array of a given type.

import { isArrayOf } from '@plq/is'

console.log(isArrayOf([], 'string')) // Output: false
console.log(isArrayOf(['a', 'b', 'c'], 'string')) // Output: true
console.log(isArrayOf(['a', 'b', 'c'], 'number')) // Output: false
console.log(isArrayOf(['a', 'b', 3], 'string')) // Output: false

isObject

Checks if a given value is an object.

import { isObject } from '@plq/is'

console.log(isObject({})) // Output: true
console.log(isObject(() => {})) // Output: false

isObjectLike

Checks if a given value is an object-like.

import { isObjectLike } from '@plq/is'

console.log(isObjectLike({})) // Output: true
console.log(isObjectLike([])) // Output: true
console.log(isObjectLike(() => {})) // Output: false

isPlainObject

Checks if a given value is a plain object.

import { isPlainObject } from '@plq/is'

console.log(isPlainObject({})) // Output: true
console.log(isPlainObject(Object.create(null))) // Output: true
console.log(isPlainObject(() => {})) // Output: false

isNull

Checks if a given value is null.

import { isNull } from '@plq/is'

console.log(isNull(null)) // Output: true
console.log(isNull(undefined)) // Output: false

isUndefined

Checks if a given value is undefined.

import { isUndefined } from '@plq/is'

console.log(isUndefined(undefined)) // Output: true
console.log(isUndefined(null)) // Output: false

isString

Checks if a given value is a string.

import { isString } from '@plq/is'

console.log(isString('')) // Output: true
console.log(isString(1)) // Output: false

isNumber

Checks if a given value is a number.

import { isNumber } from '@plq/is'

console.log(isNumber(1)) // Output: true
console.log(isNumber(NaN)) // Output: true
console.log(isNumber('')) // Output: false

isNaN

Checks if a given value is NaN.

import { isNaN } from '@plq/is'

console.log(isNaN(NaN)) // Output: true
console.log(isNaN(1)) // Output: false

isBigInt

Checks if a given value is a BigInt.

import { isBigInt } from '@plq/is'

console.log(isBigInt(BigInt(1))) // Output: true
console.log(isBigInt(1)) // Output: false

isBoolean

Checks if a given value is a boolean.

import { isBoolean } from '@plq/is'

console.log(isBoolean(true)) // Output: true
console.log(isBoolean(false)) // Output: true
console.log(isBoolean(1)) // Output: false

isSymbol

Checks if a given value is a symbol.

import { isSymbol } from '@plq/is'

console.log(isSymbol(Symbol())) // Output: true
console.log(isSymbol(1)) // Output: false

isDate

Checks if a given value is a date.

import { isDate } from '@plq/is'

console.log(isDate(new Date())) // Output: true
console.log(isDate('2021-01-01')) // Output: false

isRegExp

Checks if a given value is a regular expression.

import { isRegExp } from '@plq/is'

console.log(isRegExp(/test/)) // Output: true
console.log(isRegExp('test')) // Output: false

isSet

Checks if a given value is a Set.

import { isSet } from '@plq/is'

console.log(isSet(new Set())) // Output: true
console.log(isSet([])) // Output: false

isMap

Checks if a given value is a Map.

import { isMap } from '@plq/is'

console.log(isMap(new Map())) // Output: true
console.log(isMap([])) // Output: false

isWeakSet

Checks if a given value is a WeakSet.

import { isWeakSet } from '@plq/is'

console.log(isWeakSet(new WeakSet())) // Output: true
console.log(isWeakSet([])) // Output: false

isWeakMap

Checks if a given value is a WeakMap.

import { isWeakMap } from '@plq/is'

console.log(isWeakMap(new WeakMap())) // Output: true
console.log(isWeakMap([])) // Output: false

isError

Checks if a given value is an error.

import { isError } from '@plq/is'

console.log(isError(new Error())) // Output: true
console.log(isError('Error')) // Output: false

isDataView

Checks if a given value is a DataView.

import { isDataView } from '@plq/is'

console.log(isDataView(new DataView(new ArrayBuffer(1)))) // Output: true
console.log(isDataView([])) // Output: false

isIterable

Checks if a given value is iterable.

import { isIterable } from '@plq/is'

console.log(isIterable([])) // Output: true
console.log(isIterable({})) // Output: false

isAsyncIterable

Checks if a given value is an async iterable.

import { isAsyncIterable } from '@plq/is'

console.log(isAsyncIterable(async function* () {})) // Output: true
console.log(isAsyncIterable([])) // Output: false

isPrimitive

Checks if a given value is a primitive.

import { isPrimitive } from '@plq/is'

console.log(isPrimitive('')) // Output: true
console.log(isPrimitive(1)) // Output: true
console.log(isPrimitive(true)) // Output: true
console.log(isPrimitive(Symbol())) // Output: true
console.log(isPrimitive(null)) // Output: true
console.log(isPrimitive(undefined)) // Output: true
console.log(isPrimitive({})) // Output: false
console.log(isPrimitive([])) // Output: false

isEmpty

Checks if a given value is empty.

import { isEmpty } from '@plq/is'

console.log(isEmpty('')) // Output: true
console.log(isEmpty(0)) // Output: false
console.log(isEmpty(NaN)) // Output: true
console.log(isEmpty([])) // Output: true
console.log(isEmpty({})) // Output: true
console.log(isEmpty(new Set())) // Output: true
console.log(isEmpty(new Map())) // Output: true
console.log(isEmpty(() => {})) // Output: false

isEmptyString

Checks if a given value is an empty string.

import { isEmptyString } from '@plq/is'

console.log(isEmptyString('')) // Output: true
console.log(isEmptyString(' ')) // Output: false
console.log(isEmptyString('test')) // Output: false

isEmptyArray

Checks if a given value is an empty array.

import { isEmptyArray } from '@plq/is'

console.log(isEmptyArray([])) // Output: true
console.log(isEmptyArray([1])) // Output: false

isEmptyObject

Checks if a given value is an empty object.

import { isEmptyObject } from '@plq/is'

console.log(isEmptyObject({})) // Output: true
console.log(isEmptyObject({ a: 1 })) // Output: false

isEmptySet

Checks if a given value is an empty Set.

import { isEmptySet } from '@plq/is'

console.log(isEmptySet(new Set())) // Output: true
console.log(isEmptySet(new Set([1]))) // Output: false

isEmptyMap

Checks if a given value is an empty Map.

import { isEmptyMap } from '@plq/is'

console.log(isEmptyMap(new Map())) // Output: true
console.log(isEmptyMap(new Map([['a', 1]]))) // Output: false

isClass

Checks if a given value is a class.

import { isClass } from '@plq/is'

class Test {}

console.log(isClass(Test)) // Output: true
console.log(isClass(new Test())) // Output: false
console.log(isClass(() => {})) // Output: false

isArguments

Checks if a given value is an arguments object.

import { isArguments } from '@plq/is'

const args = (function() {
	return arguments
})()

console.log(isArguments(args)) // Output: true
console.log(isArguments([])) // Output: false

Development

Install dependencies

npm install

Lint

We use ESLint and @typescript-eslint/eslint-plugin to lint our code.
Check out .eslintrc.json

npm run lint

Run tests

We use Jest to test our code.

npm test

Build

We use TypeScript to build our code.

npm run build

Dev check list

• Add new file to src/ulils folder like is-object.ts
• Write a function isObject in is-object.ts
• Add new function to src/index.ts like export { default as isObject } from './utils/is-object'
• Add new test to __tests__/tests.ts file like describe('isObject', () => { tests('object', isObject) })
• Run npm run lint
• Run npm run test
• Commit and push your changes
• Create a pull request