enricomarino/is

The definitive JavaScript type testing library

JavaScript

194

216 commits

updated Oct 24, 2025

See the code

README

is Version Badge

Build Status dependency status dev dependency status License Downloads

npm badge

browser support

The definitive JavaScript type testing library

To be or not to be? This is the library!

Installation

As a node.js module

$ npm install is

As a component

$ component install enricomarino/is

API

general

  • is.a (value, type) or is.type (value, type)
  • is.defined (value)
  • is.empty (value)
  • is.equal (value, other)
  • is.hosted (value, host)
  • is.instance (value, constructor)
  • is.instanceof (value, constructor) - deprecated, because in ES3 browsers, "instanceof" is a reserved word
  • is.nil (value)
  • is.null (value) - deprecated, because in ES3 browsers, "null" is a reserved word
  • is.undef (value)
  • is.undefined (value) - deprecated, because in ES3 browsers, "undefined" is a reserved word

arguments

  • is.args (value)
  • is.arguments (value) - deprecated, because "arguments" is a reserved word
  • is.args.empty (value)

array

  • is.array (value)
  • is.array.empty (value)
  • is.arraylike (value)

boolean

  • is.bool (value)
  • is.boolean (value) - deprecated, because in ES3 browsers, "boolean" is a reserved word
  • is.false (value) - deprecated, because in ES3 browsers, "false" is a reserved word
  • is.true (value) - deprecated, because in ES3 browsers, "true" is a reserved word

date

  • is.date (value)

element

  • is.element (value)

error

  • is.error (value)

function

  • is.fn (value)
  • is.function (value) - deprecated, because in ES3 browsers, "function" is a reserved word

number

  • is.number (value)
  • is.infinite (value)
  • is.decimal (value)
  • is.divisibleBy (value, n)
  • is.integer (value)
  • is.int (value) - deprecated, because in ES3 browsers, "int" is a reserved word
  • is.maximum (value, others)
  • is.minimum (value, others)
  • is.nan (value)
  • is.even (value)
  • is.odd (value)
  • is.ge (value, other)
  • is.gt (value, other)
  • is.le (value, other)
  • is.lt (value, other)
  • is.within (value, start, finish)

object

  • is.object (value)

regexp

  • is.regexp (value)

string

  • is.string (value)

encoded binary

  • is.base64 (value)
  • is.hex (value)

Symbols

  • is.symbol (value)

BigInts

  • is.bigint (value)

Contributors

enricomarino/is

The definitive JavaScript type testing library

JavaScript

194

216 commits

updated Oct 24, 2025

See the code

README

is Version Badge

Build Status dependency status dev dependency status License Downloads

npm badge

browser support

The definitive JavaScript type testing library

To be or not to be? This is the library!

Installation

As a node.js module

$ npm install is

As a component

$ component install enricomarino/is

API

general

  • is.a (value, type) or is.type (value, type)
  • is.defined (value)
  • is.empty (value)
  • is.equal (value, other)
  • is.hosted (value, host)
  • is.instance (value, constructor)
  • is.instanceof (value, constructor) - deprecated, because in ES3 browsers, "instanceof" is a reserved word
  • is.nil (value)
  • is.null (value) - deprecated, because in ES3 browsers, "null" is a reserved word
  • is.undef (value)
  • is.undefined (value) - deprecated, because in ES3 browsers, "undefined" is a reserved word

arguments

  • is.args (value)
  • is.arguments (value) - deprecated, because "arguments" is a reserved word
  • is.args.empty (value)

array

  • is.array (value)
  • is.array.empty (value)
  • is.arraylike (value)

boolean

  • is.bool (value)
  • is.boolean (value) - deprecated, because in ES3 browsers, "boolean" is a reserved word
  • is.false (value) - deprecated, because in ES3 browsers, "false" is a reserved word
  • is.true (value) - deprecated, because in ES3 browsers, "true" is a reserved word

date

  • is.date (value)

element

  • is.element (value)

error

  • is.error (value)

function

  • is.fn (value)
  • is.function (value) - deprecated, because in ES3 browsers, "function" is a reserved word

number

  • is.number (value)
  • is.infinite (value)
  • is.decimal (value)
  • is.divisibleBy (value, n)
  • is.integer (value)
  • is.int (value) - deprecated, because in ES3 browsers, "int" is a reserved word
  • is.maximum (value, others)
  • is.minimum (value, others)
  • is.nan (value)
  • is.even (value)
  • is.odd (value)
  • is.ge (value, other)
  • is.gt (value, other)
  • is.le (value, other)
  • is.lt (value, other)
  • is.within (value, start, finish)

object

  • is.object (value)

regexp

  • is.regexp (value)

string

  • is.string (value)

encoded binary

  • is.base64 (value)
  • is.hex (value)

Symbols

  • is.symbol (value)

BigInts

  • is.bigint (value)

Contributors

Project health

Overall

3.4/10

Maintained

0/10

Code review

0/10
OpenSSF Scorecard

npm

Latest release

3.3.2 · Jul 19, 2025

Releases this year

0