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 v10 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("")

Dependencies

This project have no dependencies.

License

MIT