is

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

• Jordan Harband

3.3.0 / 2018-12-14

• [New] add is.bigint (#36)
• [Docs] change jsdoc comments "Mixed" to wildcards (#34)
• [Tests] up to node v11.4, v10.14, v9.11, v8.14, v7.10, v6.15, v4.9; use nvm install-latest-npm
• [Dev Deps] update eslint, @ljharb/eslint-config, safe-publish-latest, tape

3.2.1 / 2017-02-27

• [Fix] is.fn: recognize generator and async functions too (#28)
• [Tests] up to node v7.5, v4.7; improve test matrix
• [Dev Deps] update @ljharb/eslint-config, eslint, tape
• [Docs] improve readme formatting (#27)

3.2.0 / 2016-10-24

• [Fix] fix infinite loop when comparing two empty arrays + fix skipping first element (#24, #25)
• [New] add is.primitive
• [New] Add is.date.valid function and tests (#19)
• [Tests] use pretest for npm run lint; add npm run tests-only
• [Tests] up to node v4.6, v5.12, v6.9; improve test matrix
• [Tests] fix description (#18)
• [Dev Deps] update tape, jscs, eslint, @ljharb/eslint-config

3.1.0 / 2015-09-20

• [Enhancement]: is.array: Prefer Array.isArray when present
• [Fix] Deprecate is.boolean/is.int (ES3 syntax errors)
• [Docs] Switch from vb.teelaun.ch to versionbadg.es for the npm version badge SVG
• [Refactor] Don't use yoda conditions
• [Refactor] is.equal can return earlier in some cases (#16)
• [Tests] Quote "throws" (ES3 syntax error)
• [Tests] up to io.js v3.3, up to node v4.1
• [Dev Deps] add npm run eslint
• [Dev Deps] update tape, covert, jscs

3.0.1 / 2015-02-22

• Version bump to resolve npm bug with v3.0.0

3.0.0 / 2015-02-21

• is.empty should return true for falsy values (#13, #14)
• All grade A-supported node/iojs versions now ship with an npm that understands ^.
• Test on iojs v1.2 and v1.3, node v0.12; speed up builds; allow failures on all but two latest minor versions.
• Update jscs

2.2.1 / 2015-02-06

• Update tape, jscs
• toString breaks in some browsers; using toStr instead.

2.2.0 / 2014-11-29

• Update tape, jscs
• Add is.symbol

2.1.0 / 2014-10-21

• Add CHANGELOG.md
• Add is.hex and is.base64 #12
• Update tape, jscs
• Lock covert to v1.0.0 substack/covert#9

2.0.2 / 2014-10-05

• undefined can be redefined in ES3 browsers.
• Update jscs.json and make style consistent
• Update foreach, jscs, tape
• Naming URLs in README

2.0.1 / 2014-09-02

• Add the license to package.json
• Add license and downloads badges
• Update jscs

2.0.0 / 2014-08-25

• Add make release
• Update copyright notice.
• Fix is.empty(new String())

1.1.0 / 2014-08-22

• Removing redundant license
• Add a non-deprecated method for is.null
• Use a more reliable valueOf coercion for is.false/is.true
• Clean up README.md
• Running npm run lint as part of tests.
• Fixing lint errors.
• Adding npm run lint
• Updating covert

1.0.0 / 2014-08-07

• Update tape, covert
• Increase code coverage
• Update LICENSE.md, README.md

0.3.0 / 2014-03-02

• Update tape, covert
• Adding npm run coverage
• is.arguments -> is.args, because reserved words.
• "undefined" is a reserved word in ES3 browsers.
• Optimizing is.equal to return early if value and other are strictly equal.
• Fixing is.equal for objects.
• Test improvements

0.2.7 / 2013-12-26

• Update tape, foreach
• is.decimal(Infinity) shouldn't be true #11

0.2.6 / 2013-05-06

• Fix lots of tests #9
• Update tape #8

0.2.5 / 2013-04-24

• Use tap instead of tape #7