type-name

What is type-name?

The type-name npm package is used to get the name of a JavaScript value's type. It is particularly useful for debugging and logging purposes, where knowing the exact type of a value can be crucial.

What are type-name's main functionalities?

Basic Type Identification

This feature allows you to identify the basic types of JavaScript values such as numbers, strings, and booleans.

const typeName = require('type-name');
console.log(typeName(123)); // 'Number'
console.log(typeName('hello')); // 'String'
console.log(typeName(true)); // 'Boolean'

Object Type Identification

This feature helps in identifying the types of more complex objects like arrays, dates, and plain objects.

const typeName = require('type-name');
console.log(typeName({})); // 'Object'
console.log(typeName([])); // 'Array'
console.log(typeName(new Date())); // 'Date'

Custom Class Type Identification

This feature allows you to identify instances of custom classes, which can be particularly useful in larger codebases with many custom types.

const typeName = require('type-name');
class MyClass {}
console.log(typeName(new MyClass())); // 'MyClass'

Other packages similar to type-name

typeof

The 'typeof' operator is a built-in JavaScript operator that returns a string indicating the type of the unevaluated operand. While it is more limited compared to type-name, it is a native feature and does not require any additional package.

type-detect

The 'type-detect' package is another npm package that provides type detection for JavaScript values. It offers more detailed type information compared to the built-in 'typeof' operator and is similar in functionality to type-name.

kind-of

The 'kind-of' package is a utility for getting the native type of a value. It is similar to type-name but offers additional features like checking if a value is a buffer, stream, or other specific types.

README

type-name

Just a reasonable typeof

DESCRIPTION

typeName function returns reasonable type name for input value.

description	input	result
null literal	null	'null'
undefined value	undefined	'undefined'
string literal	'foo'	'string'
number literal	5	'number'
boolean literal	false	'boolean'
regexp literal (Android 4.1+)	/^not/	'RegExp'
array literal	['foo', 4]	'Array'
object literal	{name: 'bar'}	'Object' (be careful!)
function expression	function () {}	'function'
String object	new String('foo')	'String'
Number object	new Number('3')	'Number'
Boolean object	new Boolean('1')	'Boolean'
Date object	new Date()	'Date'
RegExp object (Android 4.1+)	new RegExp('^not', 'g')	'RegExp'
Array object	new Array()	'Array'
Object object	new Object()	'Object'
Function object	new Function('x', 'y', 'return x + y')	'function' (be careful!)
Error object	new Error('error!')	'Error'
TypeError object	new TypeError('type error!')	'TypeError'
NaN	NaN	'number'
Infinity	Infinity	'number'
Math	Math	'Math'
JSON (IE8+)	JSON	'JSON'
arguments object (IE9+)	(function(){ return arguments; })()	'Arguments'
User-defined constructor	new Person('alice', 5)	'Person'
Anonymous constructor	new AnonPerson('bob', 4)	''
Named class	new(class Foo { constructor() {} })	'Foo'
Anonymous class	new(class { constructor() {} })	''
Symbol	Symbol("FOO")	'symbol'
Promise	Promise.resolve(1)	'Promise'

EXAMPLE

var typeName = require('type-name');
var assert = require('assert');

assert(typeName(null) === 'null');
assert(typeName(undefined) === 'undefined');
assert(typeName('foo') === 'string');
assert(typeName(5) === 'number');
assert(typeName(false) === 'boolean');
assert(typeName(/^not/) === 'RegExp');
assert(typeName(['foo', 4]) === 'Array');
assert(typeName({name: 'bar'}) === 'Object');
assert(typeName(function () {}) === 'function');
assert(typeName(new String('foo')) === 'String');
assert(typeName(new Number('3')) === 'Number');
assert(typeName(new Boolean('1')) === 'Boolean');
assert(typeName(new Date()) === 'Date');
assert(typeName(new RegExp('^not', 'g')) === 'RegExp');
assert(typeName(new Array()) === 'Array');
assert(typeName(new Object()) === 'Object');
assert(typeName(new Function('x', 'y', 'return x + y')) === 'function');
assert(typeName(new Error('error!')) === 'Error');
assert(typeName(new TypeError('type error!')) === 'TypeError');
assert(typeName(NaN) === 'number');
assert(typeName(Infinity) === 'number');
assert(typeName(Math) === 'Math');
assert(typeName(JSON) === 'JSON'); // IE8+
assert(typeName((function(){ return arguments; })()) === 'Arguments');  // IE9+
assert(typeName(Symbol("FOO")) === 'symbol');
assert(typeName(Promise.resolve(1)) === 'Promise');

function Person(name, age) {
    this.name = name;
    this.age = age;
}

var AnonPerson = function(name, age) {
    this.name = name;
    this.age = age;
};

assert(typeName(new Person('alice', 5)) === 'Person');
assert(typeName(new AnonPerson('bob', 4)) === '');

assert(typeName(new(class Foo { constructor() {} })) === 'Foo');
assert(typeName(new(class { constructor() {} })) === '');

INSTALL

via npm

Install

$ npm install --save type-name

Use

var typeName = require('type-name');
console.log(typeName(anyVar));

use type-name npm module on browser

typeName function is exported

<script type="text/javascript" src="./path/to/node_modules/type-name/build/type-name.js"></script>

via bower

Install

$ bower install --save type-name

Load (typeName function is exported)

<script type="text/javascript" src="./path/to/bower_components/type-name/build/type-name.js"></script>

Use

console.log(typeName(anyVar));

AUTHOR

• Takuto Wada

CONTRIBUTORS

• azu
• Yosuke Furukawa
• Athan
• Andrew Moss

LICENSE

Licensed under the MIT license.

Changelog

2.0.2 (2016-07-27)

Bug Fixes

• Fix crash when called with an es6 anonymous class instance (by @inversion)