what-is-that

Minimal, tiny (1.1 kb) object type identifier for both Node.js and browser written in TypeScript.

Feature

• Minimal: simply detect the type for any objects.
• Fast: it's basically an if statement.
• Tiny: only 1.1kb of gzipped.

compatible to ES3+

Install

npm install what-is-that

Usage

import {what, isObject, isObjectLike} from 'what-is-that'

// 'Boolean'
what(true)

// 'String'
what('that')

/** Detect whether it's a Plain object or any other (ex. custom class instance) */

// 'Object'
what({is: 'that'})

class MyObj {}

const obj = new MyObj()

// 'ObjectLike'
what(obj)

// false
isObject(obj)

// true
isObjectLike(obj)

API

what(o: any): Type

Returns a string representation of the type of argument or "Unknown" if it can't be identified.

The return value will be one of the list below.

• "Undefined"
• "Null"
• "Number"
• "Boolean"
• "String"
• "Symbol"
• "BigInt"
• "Object"
• "ObjectLike"
• "Function"
• "GeneratorFunction"
• "Generator"
• "RegExp"
• "Date"
• "Promise"
• "Error"
• "TextEncoder"
• "TextDecoder"
• "URL"
• "URLSearchParams"
• "Array"
• "Set"
• "Map"
• "WeakSet"
• "WeakMap"
• "DataView"
• "Buffer"
• "ArrayBuffer"
• "SharedArrayBuffer"
• "Int8Array"
• "Uint8Array"
• "Uint8ClampedArray"
• "Int16Array"
• "Uint16Array"
• "Int32Array"
• "Uint32Array"
• "Float32Array"
• "Float64Array"
• "BigInt64Array"
• "BigUint64Array"
• "Blob"
• "File"
• "Unknown"

Detection

Functions which return true if the argument is a value or instance of the corresponding object type, false if not.

• isUndefined (o: any): o is undefined
• isNull (o: any): o is null
• isNumber (o: any): o is number
• isBoolean (o: any): o is boolean
• isString (o: any): o is string
• isSymbol (o: any): o is Symbol
• isBigInt (o: any): o is BigInt
• isObject (o: any): o is Record<string, any>
• isObjectLike (o: any): o is Record<string | number | symbol, any>
• isFunction (o: any): o is Function
• isGeneratorFunction (o: any): o is GeneratorFunction
• isGenerator (o: any): o is Generator
• isRegExp (o: any): o is RegExp
• isDate (o: any): o is Date
• isPromise (o: any): o is Promise
• isError (o: any): o is Error
• isTextEncoder (o: any): o is TextEncoder
• isTextDecoder (o: any): o is TextDecoder
• isURL (o: any): o is URL
• isURLSearchParams (o: any): o is URLSearchParams
• isArray (o: any): o is Array
• isSet (o: any): o is Set
• isMap (o: any): o is Map<any, any>
• isWeakSet (o: any): o is WeakSet
• isWeakMap (o: any): o is WeakMap<any, any>
• isDataView (o: any): o is DataView
• isBuffer (o: any): o is Buffer
• isArrayBuffer (o: any): o is ArrayBuffer
• isSharedArrayBuffer (o: any): o is SharedArrayBuffer
• isInt8Array (o: any): o is Int8Array
• isUint8Array (o: any): o is Uint8Array
• isUint8ClampedArray (o: any): o is Uint8ClampedArray
• isInt16Array (o: any): o is Int16Array
• isUint16Array (o: any): o is Uint16Array
• isInt32Array (o: any): o is Int32Array
• isUint32Array (o: any): o is Uint32Array
• isFloat32Array (o: any): o is Float32Array
• isFloat64Array (o: any): o is Float64Array
• isBigInt64Array (o: any): o is BigInt64Array
• isBigUint64Array (o: any): o is BigUint64Array
• isBlob (o: any): o is Blob
• isFile (o: any): o is File
• isUnknown (o: any): o is unknown

For TypeScript

There are some additional functions for generic object types which would be useful to ensure that the object is explicitly typed.

• isObjectAs <T extends Record<string, any>>(o: any): o is T
• isObjectLikeAs <T extends Record<string | number | symbol, any>>(o:any): o is T
• isFunctionAs <T extends (...args: any[]) => any>(o: any): o is T
• isGeneratorAs (o: any): o is T
• isPromiseAs <T extends Promise>(o: any): o is T
• isArrayAs <T extends Array>(o: any): o is T
• isSetAs <T extends Set>(o: any): o is T
• isMapAs <T extends Map<any, any>>(o: any): o is T
• isWeakSetAs <T extends WeakSet>(o: any): o is T
• isWeakMapAs <T extends WeakMap<any, any>>(o: any): o is T
• isUnknownAs (o: any): o is T