is

What is is?

The 'is' npm package provides a set of utility functions for type checking and validation. It allows developers to easily determine the type of a variable, check for specific conditions, and validate data types.

What are is's main functionalities?

Type Checking

The 'is' package provides functions to check the type of a variable. For example, 'is.string' checks if a value is a string, 'is.number' checks if a value is a number, and 'is.array' checks if a value is an array.

const is = require('is');

console.log(is.string('hello')); // true
console.log(is.number(123)); // true
console.log(is.array([1, 2, 3])); // true

Existence Checks

The 'is' package includes functions to check for the existence and truthiness of values. 'is.empty' checks if a value is empty, 'is.existy' checks if a value exists (is not null or undefined), and 'is.truthy' checks if a value is truthy.

const is = require('is');

console.log(is.empty([])); // true
console.log(is.existy(null)); // false
console.log(is.truthy(1)); // true

Regex and String Checks

The 'is' package provides functions to validate strings against common patterns. For example, 'is.email' checks if a string is a valid email address, 'is.url' checks if a string is a valid URL, and 'is.creditCard' checks if a string is a valid credit card number.

const is = require('is');

console.log(is.email('[e-mail]')); // true
console.log(is.url('https://www.example.com')); // true
console.log(is.creditCard('4111111111111111')); // true

Other packages similar to is

lodash

Lodash is a modern JavaScript utility library that provides a wide range of functions for common programming tasks, including type checking and validation. It offers similar functionality to 'is' but with a broader scope and additional utilities for working with arrays, objects, and more.

validator

Validator is a library for string validation and sanitization. It provides a comprehensive set of functions for validating and sanitizing strings, including checks for email addresses, URLs, and credit card numbers. It is more focused on string validation compared to 'is'.

type-detect

Type-detect is a library for type detection in JavaScript. It provides functions to determine the type of a variable, similar to the type checking features of 'is'. It is a lightweight alternative focused specifically on type detection.

README

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.boolean (value)
• 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.int (value)
• 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)

Contributors

• Jordan Harband