is-check

Check if the given value is of a specific type.

Usage no npm install needed!

<script type="module">
  import isCheck from 'https://cdn.skypack.dev/is-check';
</script>

README

is-check

Check if the given value is of a specific type.

About

Provide a simple and clean way to check if a value matches a specific type. Abstract the usage of "typeof === '...'".

Installation

npm install is-check

Module Usage

var check = require('is-check');

var myValue = 'something';
check.isArray(myValue);
check.isBoolean(myValue);
check.isFunction(myValue);
check.isNil(myValue);
check.isNull(myValue);
check.isNumber(myValue);
check.isObject(myValue);
check.isString(myValue);
check.isUndefined(myValue);

Running the tests

From inside the root project folder run:

npm install

and then if you are on a windows machine:

npm test

if you are on a unix machine:

npm testUNIX

Spec

TOC

function isArray()

returns true:

isArray([]) should be true.

check.isArray([]).should.be.ok;

isArray([1]) should be true.

check.isArray([1]).should.be.ok;

isArray([new Array()]) should be true.

check.isArray([new Array()]).should.be.ok;

isArray([Array.prototype]) should be true.

check.isArray([Array.prototype]).should.be.ok;

returns false:

isArray(37) should be false.

check.isArray(37).should.not.be.ok;

isArray(3.14) should be false.

check.isArray(3.14).should.not.be.ok;

isArray(Math.LN2) should be false.

check.isArray(Math.LN2).should.not.be.ok;

isArray(Infinity) should be false.

check.isArray(Infinity).should.not.be.ok;

isArray(Number(1)) should be false.

check.isArray(Number(1)).should.not.be.ok;

isArray(NaN) should be false.

check.isArray(NaN).should.not.be.ok;

isArray("") should be false.

check.isArray("").should.not.be.ok;

isArray("bla") should be false.

check.isArray("bla").should.not.be.ok;

isArray(typeof 1) should be false.

check.isArray(typeof 1).should.not.be.ok;

isArray("abc") should be false.

check.isArray("abc").should.not.be.ok;

isArray(false) should be false.

check.isArray(false).should.not.be.ok;

isArray(false) should be false.

check.isArray(false).should.not.be.ok;

isArray(Boolean(false)) should be false.

check.isArray(Boolean(false)).should.not.be.ok;

isArray(Boolean(false)) should be false.

check.isArray(Boolean(false)).should.not.be.ok;

isArray( new Boolean(false)) should be false.

check.isArray(Boolean( new Boolean(false))).should.not.be.ok;

isArray(undefined) should be false.

check.isArray(undefined).should.not.be.ok;

isArray(null) should be false.

check.isArray(null).should.not.be.ok;

isArray({a:1}) should be false.

check.isArray({a:1}).should.not.be.ok;

isArray(new Date()) should be false.

check.isArray(new Date()).should.not.be.ok;

isArray(function(){}) should be false.

check.isArray(function(){}).should.not.be.ok;

isArray(Math.sin) should be false.

check.isArray(Math.sin).should.not.be.ok;

function isBoolean()

returns true:

isBoolean(true) should be true.

check.isBoolean(true).should.be.ok;

isBoolean(false) should be true.

check.isBoolean(false).should.be.ok;

isBoolean(Boolean(true)) should be true.

check.isBoolean(Boolean(true)).should.be.ok;

isBoolean(Boolean(false)) should be true.

check.isBoolean(Boolean(false)).should.be.ok;

returns false:

isBoolean(NaN) should be false.

check.isBoolean(NaN).should.not.be.ok;

isBoolean(undefined) should be false.

check.isBoolean(undefined).should.not.be.ok;

isBoolean(null) should be false.

check.isBoolean(null).should.not.be.ok;

isBoolean({a:1}) should be false.

check.isBoolean({a:1}).should.not.be.ok;

isBoolean(new Date()) should be false.

check.isBoolean(new Date()).should.not.be.ok;

isBoolean(function(){}) should be false.

check.isBoolean(function(){}).should.not.be.ok;

isBoolean(Math.sin) should be false.

check.isBoolean(Math.sin).should.not.be.ok;

isBoolean([1, 2, 4]) should be false.

check.isBoolean([1, 2, 4]).should.not.be.ok;

isBoolean(37) should be false.

check.isBoolean(37).should.not.be.ok;

isBoolean(3.14) should be false.

check.isBoolean(3.14).should.not.be.ok;

isBoolean(Math.LN2) should be false.

check.isBoolean(Math.LN2).should.not.be.ok;

isBoolean(Infinity) should be false.

check.isBoolean(Infinity).should.not.be.ok;

isBoolean(Number(1)) should be false.

check.isBoolean(Number(1)).should.not.be.ok;

isBoolean("") should be false.

check.isBoolean("").should.not.be.ok;

isBoolean("bla") should be false.

check.isBoolean("bla").should.not.be.ok;

isBoolean(typeof 1) should be false.

check.isBoolean(typeof 1).should.not.be.ok;

isBoolean("abc") should be false.

check.isBoolean("abc").should.not.be.ok;

function isFunction()

returns true:

isFunction(function(){}) should be true.

check.isFunction(function(){}).should.be.ok;

isFunction(Math.sin) should be true.

check.isFunction(Math.sin).should.be.ok;

returns false:

isFunction(37) should be false.

check.isFunction(37).should.not.be.ok;

isFunction(3.14) should be false.

check.isFunction(3.14).should.not.be.ok;

isFunction(Math.LN2) should be false.

check.isFunction(Math.LN2).should.not.be.ok;

isFunction(Infinity) should be false.

check.isFunction(Infinity).should.not.be.ok;

isFunction(Number(1)) should be false.

check.isFunction(Number(1)).should.not.be.ok;

isFunction(NaN) should be false.

check.isFunction(NaN).should.not.be.ok;

isFunction("") should be false.

check.isFunction("").should.not.be.ok;

isFunction("bla") should be false.

check.isFunction("bla").should.not.be.ok;

isFunction(typeof 1) should be false.

check.isFunction(typeof 1).should.not.be.ok;

isFunction("abc") should be false.

check.isFunction("abc").should.not.be.ok;

isFunction(true) should be false.

check.isFunction(true).should.not.be.ok;

isFunction(false) should be false.

check.isFunction(false).should.not.be.ok;

isFunction(Boolean(true)) should be false.

check.isFunction(Boolean(true)).should.not.be.ok;

isFunction(Boolean(false)) should be false.

check.isFunction(Boolean(false)).should.not.be.ok;

isFunction( new Boolean(true)) should be false.

check.isFunction(Boolean( new Boolean(true))).should.not.be.ok;

isFunction(undefined) should be false.

check.isFunction(undefined).should.not.be.ok;

isFunction(null) should be false.

check.isFunction(null).should.not.be.ok;

isFunction({a:1}) should be false.

check.isFunction({a:1}).should.not.be.ok;

isFunction(new Date()) should be false.

check.isFunction(new Date()).should.not.be.ok;

isFunction([1, 2, 4]) should be false.

check.isFunction([1, 2, 4]).should.not.be.ok;

function isNill()

returns true:

isNil(null) should be true.

check.isNil(null).should.be.ok;

isNil(undefined) should be true.

check.isNil(undefined).should.be.ok;

returns false:

isNil(NaN) should be false.

check.isNil(NaN).should.not.be.ok;

isNil("") should be false.

check.isNil("").should.not.be.ok;

isNil("bla") should be false.

check.isNil("bla").should.not.be.ok;

isNil(typeof 1) should be false.

check.isNil(typeof 1).should.not.be.ok;

isNil("abc") should be false.

check.isNil("abc").should.not.be.ok;

isNil(true) should be false.

check.isNil(true).should.not.be.ok;

isNil(false) should be false.

check.isNil(false).should.not.be.ok;

isNil(Boolean(true)) should be false.

check.isNil(Boolean(true)).should.not.be.ok;

isNil(Boolean(false)) should be false.

check.isNil(Boolean(false)).should.not.be.ok;

isNil( new Boolean(true)) should be false.

check.isNil(Boolean( new Boolean(true))).should.not.be.ok;

isNil({a:1}) should be false.

check.isNil({a:1}).should.not.be.ok;

isNil(new Date()) should be false.

check.isNil(new Date()).should.not.be.ok;

isNil(function(){}) should be false.

check.isNil(function(){}).should.not.be.ok;

isNil(Math.sin) should be false.

check.isNil(Math.sin).should.not.be.ok;

isNil([1, 2, 4]) should be false.

check.isNil([1, 2, 4]).should.not.be.ok;

isNil(37) should be false.

check.isNil(37).should.not.be.ok;

isNil(3.14) should be false.

check.isNil(3.14).should.not.be.ok;

isNil(Math.LN2) should be false.

check.isNil(Math.LN2).should.not.be.ok;

isNil(Infinity) should be false.

check.isNil(Infinity).should.not.be.ok;

isNil(Number(1)) should be false.

check.isNil(Number(1)).should.not.be.ok;

function isNull()

returns true:

isNull(null) should be true.

check.isNull(null).should.be.ok;

returns false:

isNull(37) should be false.

check.isNull(37).should.not.be.ok;

isNull(3.14) should be false.

check.isNull(3.14).should.not.be.ok;

isNull(Math.LN2) should be false.

check.isNull(Math.LN2).should.not.be.ok;

isNull(Infinity) should be false.

check.isNull(Infinity).should.not.be.ok;

isNull(Number(1)) should be false.

check.isNull(Number(1)).should.not.be.ok;

isNull(NaN) should be false.

check.isNull(NaN).should.not.be.ok;

isNull("") should be false.

check.isNull("").should.not.be.ok;

isNull("bla") should be false.

check.isNull("bla").should.not.be.ok;

isNull(typeof 1) should be false.

check.isNull(typeof 1).should.not.be.ok;

isNull("abc") should be false.

check.isNull("abc").should.not.be.ok;

isNull(true) should be false.

check.isNull(true).should.not.be.ok;

isNull(false) should be false.

check.isNull(false).should.not.be.ok;

isNull(Boolean(true)) should be false.

check.isNull(Boolean(true)).should.not.be.ok;

isNull(Boolean(false)) should be false.

check.isNull(Boolean(false)).should.not.be.ok;

isNull( new Boolean(true)) should be false.

check.isNull(Boolean( new Boolean(true))).should.not.be.ok;

isNull(undefined) should be false.

check.isNull(undefined).should.not.be.ok;

isNull({a:1}) should be false.

check.isNull({a:1}).should.not.be.ok;

isNull(new Date()) should be false.

check.isNull(new Date()).should.not.be.ok;

isNull(function(){}) should be false.

check.isNull(function(){}).should.not.be.ok;

isNull(Math.sin) should be false.

check.isNull(Math.sin).should.not.be.ok;

isNull([1, 2, 4]) should be false.

check.isNull([1, 2, 4]).should.not.be.ok;

function isNumber()

returns true:

isNumber(37) should be true.

check.isNumber(37).should.be.ok;

isNumber(3.14) should be true.

check.isNumber(3.14).should.be.ok;

isNumber(Math.LN2) should be true.

check.isNumber(Math.LN2).should.be.ok;

isNumber(Infinity) should be true.

check.isNumber(Infinity).should.be.ok;

isNumber(Number(1)) should be true.

check.isNumber(Number(1)).should.be.ok;

returns false:

isNumber(NaN) should be false.

check.isNumber(NaN).should.not.be.ok;

isNumber("") should be false.

check.isNumber("").should.not.be.ok;

isNumber("bla") should be false.

check.isNumber("bla").should.not.be.ok;

isNumber(typeof 1) should be false.

check.isNumber(typeof 1).should.not.be.ok;

isNumber("abc") should be false.

check.isNumber("abc").should.not.be.ok;

isNumber(true) should be false.

check.isNumber(true).should.not.be.ok;

isNumber(false) should be false.

check.isNumber(false).should.not.be.ok;

isNumber(Boolean(true)) should be false.

check.isNumber(Boolean(true)).should.not.be.ok;

isNumber(Boolean(false)) should be false.

check.isNumber(Boolean(false)).should.not.be.ok;

isNumber( new Boolean(true)) should be false.

check.isNumber(Boolean( new Boolean(true))).should.not.be.ok;

isNumber(undefined) should be false.

check.isNumber(undefined).should.not.be.ok;

isNumber(null) should be false.

check.isNumber(null).should.not.be.ok;

isNumber({a:1}) should be false.

check.isNumber({a:1}).should.not.be.ok;

isNumber(new Date()) should be false.

check.isNumber(new Date()).should.not.be.ok;

isNumber(function(){}) should be false.

check.isNumber(function(){}).should.not.be.ok;

isNumber(Math.sin) should be false.

check.isNumber(Math.sin).should.not.be.ok;

isNumber([1, 2, 4]) should be false.

check.isNumber([1, 2, 4]).should.not.be.ok;

function isObject()

returns true:

isObject({a:1}) should be true.

check.isObject({a:1}).should.be.ok;

isObject(new Date()) should be true.

check.isObject(new Date()).should.be.ok;

isObject(new Boolean(true)) should be true.

check.isObject(new Boolean(true)).should.be.ok;

returns false:

isObject(37) should be false.

check.isObject(37).should.not.be.ok;

isObject(3.14) should be false.

check.isObject(3.14).should.not.be.ok;

isObject(Math.LN2) should be false.

check.isObject(Math.LN2).should.not.be.ok;

isObject(Infinity) should be false.

check.isObject(Infinity).should.not.be.ok;

isObject(Number(1)) should be false.

check.isObject(Number(1)).should.not.be.ok;

isObject(NaN) should be false.

check.isObject(NaN).should.not.be.ok;

isObject("") should be false.

check.isObject("").should.not.be.ok;

isObject("bla") should be false.

check.isObject("bla").should.not.be.ok;

isObject(typeof 1) should be false.

check.isObject(typeof 1).should.not.be.ok;

isObject("abc") should be false.

check.isObject("abc").should.not.be.ok;

isObject(true) should be false.

check.isObject(true).should.not.be.ok;

isObject(false) should be false.

check.isObject(false).should.not.be.ok;

isObject(Boolean(true)) should be false.

check.isObject(Boolean(true)).should.not.be.ok;

isObject(Boolean(false)) should be false.

check.isObject(Boolean(false)).should.not.be.ok;

isObject( new Boolean(true)) should be false.

check.isObject(Boolean( new Boolean(true))).should.not.be.ok;

isObject(undefined) should be false.

check.isObject(undefined).should.not.be.ok;

isObject(null) should be false.

check.isObject(null).should.not.be.ok;

isObject(function(){}) should be false.

check.isObject(function(){}).should.not.be.ok;

isObject(Math.sin) should be false.

check.isObject(Math.sin).should.not.be.ok;

isObject([1, 2, 4]) should be false.

check.isObject([1, 2, 4]).should.not.be.ok;

function isString()

returns true:

isString("") should be true.

check.isString("").should.be.ok;

isString("bla") should be true.

check.isString("bla").should.be.ok;

isString(typeof 1) should be true.

check.isString(typeof 1).should.be.ok;

isString("abc") should be true.

check.isString("abc").should.be.ok;

returns false:

isString(NaN) should be false.

check.isString(NaN).should.not.be.ok;

isString(true) should be false.

check.isString(true).should.not.be.ok;

isString(false) should be false.

check.isString(false).should.not.be.ok;

isString(Boolean(true)) should be false.

check.isString(Boolean(true)).should.not.be.ok;

isString(Boolean(false)) should be false.

check.isString(Boolean(false)).should.not.be.ok;

isString( new Boolean(true)) should be false.

check.isString(Boolean( new Boolean(true))).should.not.be.ok;

isString(undefined) should be false.

check.isString(undefined).should.not.be.ok;

isString(null) should be false.

check.isString(null).should.not.be.ok;

isString({a:1}) should be false.

check.isString({a:1}).should.not.be.ok;

isString(new Date()) should be false.

check.isString(new Date()).should.not.be.ok;

isString(function(){}) should be false.

check.isString(function(){}).should.not.be.ok;

isString(Math.sin) should be false.

check.isString(Math.sin).should.not.be.ok;

isString([1, 2, 4]) should be false.

check.isString([1, 2, 4]).should.not.be.ok;

isString(37) should be false.

check.isString(37).should.not.be.ok;

isString(3.14) should be false.

check.isString(3.14).should.not.be.ok;

isString(Math.LN2) should be false.

check.isString(Math.LN2).should.not.be.ok;

isString(Infinity) should be false.

check.isString(Infinity).should.not.be.ok;

isString(Number(1)) should be false.

check.isString(Number(1)).should.not.be.ok;

function isUndefined()

returns true:

isUndefined(undefined) should be true.

check.isUndefined(undefined).should.be.ok;

returns false:

isUndefined(37) should be false.

check.isUndefined(37).should.not.be.ok;

isUndefined(3.14) should be falsw.

check.isUndefined(3.14).should.not.be.ok;

isUndefined(Math.LN2) should be false.

check.isUndefined(Math.LN2).should.not.be.ok;

isUndefined(Infinity) should be false.

check.isUndefined(Infinity).should.not.be.ok;

isUndefined(Number(1)) should be false.

check.isUndefined(Number(1)).should.not.be.ok;

isUndefined(NaN) should be false.

check.isUndefined(NaN).should.not.be.ok;

isUndefined("") should be false.

check.isUndefined("").should.not.be.ok;

isUndefined("bla") should be false.

check.isUndefined("bla").should.not.be.ok;

isUndefined(typeof 1) should be false.

check.isUndefined(typeof 1).should.not.be.ok;

isUndefined("abc") should be false.

check.isUndefined("abc").should.not.be.ok;

isUndefined(true) should be false.

check.isUndefined(true).should.not.be.ok;

isUndefined(false) should be false.

check.isUndefined(false).should.not.be.ok;

isUndefined(Boolean(true)) should be false.

check.isUndefined(Boolean(true)).should.not.be.ok;

isUndefined(Boolean(false)) should be false.

check.isUndefined(Boolean(false)).should.not.be.ok;

isUndefined( new Boolean(true)) should be false.

check.isUndefined(Boolean( new Boolean(true))).should.not.be.ok;

isUndefined(null) should be false.

check.isUndefined(null).should.not.be.ok;

isUndefined({a:1}) should be false.

check.isUndefined({a:1}).should.not.be.ok;

isUndefined(new Date()) should be false.

check.isUndefined(new Date()).should.not.be.ok;

isUndefined(function(){}) should be false.

check.isUndefined(function(){}).should.not.be.ok;

isUndefined(Math.sin) should be false.

check.isUndefined(Math.sin).should.not.be.ok;

isUndefined([1, 2, 4]) should be false.

check.isUndefined([1, 2, 4]).should.not.be.ok;