What Type Is?

A simple type checking library for Node.js

Table of Contents

• Example
• Installation
• Tests
• Usage
• API

Example

const { getType, isPlainObject, isArray } = require('what-type-is')
 
getType([]) // array
isPlainObject([]) // false
isArray(['array']) // true

Installation

npm i --save what-type-is

Tests

npm test

Usage

You can import all functions or import it on-demand using destructuring assignment

Importing all functions

const it = require('what-type-is')
const message = 'Hello'
 
console.log(
  it.isString(message)
) // true

Importing on-demand

This is a great way to import only what you need to use. You can import any functions available using destructuring assignment. Just take a look at API section to know all functions you can use and import it on-demand.

const { isArray, isObject, isPlainObject isFunction } = require('what-type-is')
const messages = ['Hello', 'World', 'How are you?']
 
console.log(
  isArray(messages)
) // true
 
console.log(
  isObject(messages)
) // true
 
console.log(
  isPlainObject(messages)
) // false
 
console.log(
  isFunction(messages)
) // false

API

• getType
• isArray
• isString
• isNumber
• isBoolean
• isObject
• isPlainObject
• isFunction
• isDate
• isRegExp
• isNull
• isUndefined

getType( any )

Returns a string containing the type of the given argument.

Example

getType(['array']) // array
getType(new Date) // date
getType({}) // object

isArray( any )

Check if a given argument is an array and returns a boolean.

Example

isArray(['array']) // true
isArray('string') // false 

isString( any )

Check if a given argument is a string and returns a boolean.

Example

isString('string') // true
isString(['array']) // false 

isNumber( any )

Check if a given argument is a number and returns a boolean.

Example

isNumber(10) // true
isNumber(['array']) // false 

isBoolean( any )

Check if a given argument is a boolean and returns a boolean.

Example

isBoolean(true) // true
isBoolean(20) // false 

isObject( any )

Check if a given argument is an object according with ECMA spec and returns a boolean.

Example

isObject({}) // true
isObject(['array']) // true

isPlainObject( any )

Check if a given argument is a plain object and returns a boolean.

Example

isPlainObject({}) // true
isPlainObject(['array']) // false

isFunction( any )

Check if a given argument is a function and returns a boolean.

Example

isFunction(() => {}) // true
isFunction(undefined) // false

isDate( any )

Check if a given argument is a date object and returns a boolean.

Example

isDate(new Date) // true
isDate('27/10/2017') // false

isRegExp( any )

Check if a given argument is a regular expression and returns a boolean.

Example

isRegExp(new RegExp) // true
isRegExp(/regularexpression/i) // true

isNull( any )

Check if a given argument is a null and returns a boolean.

Example

isNull(null) // true
isNull(0) // false

isUndefined( any )

Check if a given argument is an undefined and returns a boolean.

Example

isUndefined(undefined) // true
isUndefined(null) // false

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