Package Exports

is-checker
is-checker/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (is-checker) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

This package is still under development phase!

Type of this value is.. checker! ✅

Simple and light-weight JavaScript type checker that mimics existing type checking methods.

Installation

NPM

npm install is-checker

CDN

// For latest version.
<script src="https://kevsong.com/cdn/is-checker"></script>
// Or
<script src="https://kevsong.com/cdn/is-checker@latest"></script>

// For specific version.
<script src="https://kevsong.com/cdn/is-checker@1.0.0"></script>

Import

ESM

import * as isChecker from "is-checker";

CJS

require('is-checker');

That's it. No further action needed!

Introduction

Have you tried to validate the type of a variable and wonder why some native objects provide 'is' type checking method but some don't?

For example:

const array = [1, 2, 3];
Array.isArray(array); // Works!

const number = 100;
Number.isNumber(number); // Doesn't work :(

This is why is-checker will add 'is' checker for every types in JavaScript!

const string = 'is-checker';
String.isString(string); // How convenient!

The purpose is to create something easy to remember without having to look back at package documentation. Since we already have some default methods to check certain types, why not extend them to every types?

Guide

Every types in JavaScript will have same 'is' checker method attached to it. If type doesn't have a class by default, it'll create one. Some types will have additional methods created to it.

Array

isArray()

const myArray = [];
Array.isArray(myArray) // true.

Bigint

isBigint()

const myBigint = BigInt(9007199254740991);
Bigint.isBigint(myBigint) // true.

Boolean

isBoolean()

const myBoolean = true;
Boolean.isBoolean(myBoolean) // true.

Date

isDate()

const myDate = new Date();
Date.isDate(myDate) // true.

Blob

isBlob()

const myBlob = new Blob([], {});
Blob.isBlob(myBlob) // true.

Error

isError()

const myError = new Error('');
Error.isError(myError) // true.

Function

isFunction()

const myFunction = () => null;
Function.isFunction(myFunction) // true.

Map

isMap()

const myMap = new Map();
Map.isMap(myMap) // true.

File

isFile()

const myFile = new File();
File.isFile(myFile) // true.

Null

isNull()

const myNull = null;
Null.isNull(myNull) // true.

Number

isNumber()

const myNumber = 100;
Number.isNumber(myNumber) // true.

Promise

isPromise()

const myPromise = new Promise(res => res());
Promise.isPromise(myPromise) // true.

Object

isObject()

const myObject = {};
Object.isObject(myObject) // true.

Set

isSet()

const mySet = new Set();
Set.isSet(mySet) // true.

Regexp

isRegexp()

const myRegexp = new RegExp();
Regexp.isRegexp(myRegexp) // true.

Symbol

isSymbol()

const mySymbol = Symbol();
Symbol.isSymbol(mySymbol) // true.

String

isString()

const myString = '';
String.isString(myString) // true.

Undefined

isUndefined()

const myUndefined = undefined;
Undefined.isUndefined(myUndefined) // true.

is-checker