@slimio/is NPM

SlimIO IS

Node.js JavaScript Type checker (Primitives, Objects, etc..)

Package heavily inspired by @sindresorhus/is. This package aims to work on Node.js (no browser support).

Why

Focus on type checking (no fancy feature).
Focus on Node.js support.
Come with a TypeScript definition (which works).
Is concerned about being stable.

Requirements

Node.js v16 or higher.

Getting Started

This package is available in the Node Package Repository and can be easily installed with npm or yarn.

$ npm i @slimio/is
# or
$ yarn add @slimio/is

Usage example

const { strictEqual } = require("assert");
const is = require("@slimio/is");

strictEqual(is.bool(true), true);
strictEqual(is.string("hello"), true);
strictEqual(is.map(new Map()), true);
strictEqual(is.func(() => {}), true);

The is const namespace is a Plain JavaScript Object with a lot of exported methods (check the below API Documentation).

API

All methods can be called as follow: is.{methodName}. All methods return a boolean value.

Primitives

method	example
string	`is.string("hello")`
number	`is.number(10)`
boolean	`is.boolean(true)`
bool	`is.bool(false)`
symbol	`is.symbol(Symbol("foo"))`
undefined	`is.undefined(undefined)`
bigint	`is.bigint(50n)`
nullValue	`is.nullValue(null)`
nullOrUndefined	`is.nullOrUndefined(null)`
primitive	`is.primitive("hello")`

is.null is not available because of a name restriction.

Objects

method	example
promise	`is.promise(new Promise())`
classObject	`is.classObject(new Class{})`
array	`is.array([])`
object	`is.object({})`
plainObject	`is.plainObject(Object.create(null))`
set	`is.set(new Set())`
map	`is.map(new Map())`
weakMap	`is.weakMap(new WeakMap())`
weakSet	`is.weakSet(new WeakSet())`
error	`is.error(new Error("ooppss!"))`
date	`is.date(new Date())`
regExp	`is.regExp(/^hello world$/)`
buffer	`is.buffer(Buffer.from("hello"))`

is.class is not available because of a name restriction.

Functions & Iterators

method	example
func	`is.func(new Function())`
generatorFunction	N/A
asyncFunction	`is.asyncFunction(async function() {})`
boundFunction	`is.boundFunction((function(){}).bind(null))`
iterable	`is.iterable([1, 2])`
asyncIterable	N/A
generator	N/A

is.function has been reduced to is.func because of a name restriction.

Typed Arrays

method	example
typedArray	`is.typedArray(new int8Array())`
int8Array	`is.int8Array(new int8Array())`
uint8Array	`is.uint8Array(new uint8Array())`
uint8ClampedArray	`is.uint8ClampedArray(new uint8ClampedArray())`
int16Array	`is.int16Array(new int16Array())`
uint16Array	`is.uint16Array(new uint16Array())`
int32Array	`is.int32Array(new int32Array())`
uint32Array	`is.uint32Array(new uint32Array())`
float32Array	`is.float32Array(new float32Array())`
float64Array	`is.float64Array(new float64Array())`
arrayBuffer	`is.arrayBuffer(new ArrayBuffer())`
sharedArrayBuffer	`is.sharedArrayBuffer(new SharedArrayBuffer())`
dataView	`is.dataView(new DataView(new ArrayBuffer(8)))`

Misc

method	example
nan	`is.nan(Number("booom!"))`
integer	`is.integer(5 / 10)`
directInstanceOf	`is.directInstanceOf(Object, {})`
truthy	`is.truthy(true)`
falsy	`is.falsy("")`
emptyString	`is.emptyString("")`