JSPM

Check if a string matches the name of a Node.js builtin module

Returns `true` if the given string looks like a glob pattern or an extglob pattern. This makes it easy to create code that only uses external modules like node-glob when necessary, resulting in much faster code execution and initialization time, and a bet

Returns true if an object was created by the `Object` constructor, or Object.create(null).

Check if argv has a specific flag

Check if something is a Node.js stream

Check if the process is running inside Windows Subsystem for Linux (Bash on Windows)

type-check allows you to check the types of JavaScript values at runtime with a Haskell like type syntax.

Returns true if a number or string value is a finite number. Useful for regex matches, parsing, user input, etc.

Detect whether the terminal supports Unicode

Check if a value is a plain object

Check if a value is an object

Detect the file type of a file, stream, or data

URI validation functions

Returns true if a value has the characteristics of a valid JavaScript descriptor. Works for data descriptors and accessor descriptors.

Check for outdated, incorrect, and unused dependencies.

Detect whether a terminal supports hyperlinks

Get the native type of a value.

Check if a URL is absolute

Check if your code is running as an npm script

Check if something is a promise

Returns true if a value is a plain object, array or function.

Check if the character represented by a given Unicode code point is fullwidth

Runtime library to validate data against TypeScript interfaces

Check if a value is a regular expression

Check if a Node.js Buffer or Uint8Array is UTF-8

allows easy type enforcement for all JS types objects and classes. it is also extensible and provides simple to use type checks for your own custom classes and types

Check if a path is in the current working directory

Check if a path is a file, directory, or symlink

Type check values

JavaScript Standard Style - ESLint Shareable Config

Check whether a request can be retried based on the `error.code`

unist utility to recursively walk over nodes, with ancestral information

Returns true if a value exists, false if empty. Works with deeply nested values using object paths.

Checks for URLs during typing and pasting and automatically converts them to links.

unist utility to check if a node passes a test

Returns true if the value is an object and not an array or null.

Returns true if a string has an extglob.

Update notifications for your CLI app

Check if a file path is a binary file

Lint files staged by git

[MongoDB](http://mongodb.com)-backed session storage for [connect](https://www.npmjs.org/package/connect) and [Express](http://www.expressjs.com). Meant to be a well-maintained and fully-featured replacement for modules like [connect-mongo](https://www.np

Check if something is a generator function

Check if a number is a redirect HTTP status code

Returns true if the platform is windows. UMD module, works with node.js, commonjs, browser, AMD, electron, etc.

Isomorphic, functional type-checking for Javascript

allows easy type enforcement for all JS types objects and classes. it is also extensible and provides simple to use type checks for your own custom classes and types

Check if a value is an Observable

Returns true if a value has the characteristics of a valid JavaScript data descriptor.

Returns true if a value has the characteristics of a valid JavaScript accessor descriptor.

Check whether operating system CPU architecture is 64-bit or 32-bit (Supports browsers)

mdast extension to parse and serialize GFM task list items

Get the operating system CPU architecture

A simple and composable way to validate data in JavaScript (and TypeScript).

Returns true if a file path is absolute. Does not rely on the path module and can be used as a polyfill for node.js native `path.isAbolute`.

Check if a value is a Fetch network error

Check if your package was installed globally

A little library for asserting types and values, with zero dependencies.

Drop-in replacement for `fs.existsSync` with zero dependencies. Other libs I found either have crucial differences from fs.existsSync, or unnecessary dependencies. See README.md for more info.

Check if a path is the current working directory

Check which JavaScript environment your code is running in at runtime: browser, Node.js, Bun, etc

Displays a beginner-friendly message telling your user to upgrade their version of Node

JavaScript Standard Style JSX support - ESLint Shareable Config

Check if a string is an IP address

Check if a local or remote port is reachable

Coalesce for JavaScript. Returns the first value that is not undefined or null.

Typescript-compatible minimalistic shallow equality check for arrays/objects

Returns `true` if the path appears to be relative.

Check dependencies in your node module

micromark extension to support GFM task list items

Check if the process is running in a Continuous Integration (CI) environment

Check if a file path is a text file

Returns `true` if the value is a primitive.

Function argument validation for humans

hast utility to check if a node has a property

A type checking library where each exported function returns either true or false and does not throw. Also added tests.

Binary wrapper for Flow - A static type checker for JavaScript

Check if an input value is a ssh url or not.

Check if a value is a natural number

Check TypeScript type definitions

Check if a binary is working

Test if an object has a specified property.

Validate an email address according to RFCs 5321, 5322, and others

Check whether a RegExp flag is supported

Check if a Buffer/Uint8Array is a GZIP file

Detect which package manager you're using (yarn or npm)

Detect the archive type of a Buffer/Uint8Array

Test if a value is object-like.

Update notifications for your CLI app, maintained in CommonJS (CJS)

Wrap your standards in a tortilla and cover it in special sauce.

Test if a value is an array.

Return a function which tests if every element in an array passes a test condition.

Validates if a value is an array.

Determine the name of a value's constructor.

Check if an environment is big endian.

Test if a double-precision floating-point numeric value is infinite.

Validates if a value is a number.

Test if a value is a string.

Test if a value is a boolean.

Test if a value is a regular expression.

Test if a value is a function.

Returns true if a windows file path has invalid characters.

Return true if a value is a valid glob pattern or patterns.

Check if a module ID is resolvable with require()

Test if a value is a Float64Array.

Test if a double-precision floating-point numeric value is NaN.

Test if a value is a Uint32Array.

Test if a value is a Buffer object.

Test if a value is a plain object.

Test if a value is an object.

Test whether a path exists on the filesystem.

Check if mobile browser.

Test if a value is a Float32Array.

Test if a value is a number.

Test if a value is a regular expression string.

A straightforward implementation of base58-check encoding

Detect the archive type of a Buffer/Uint8Array

Validates if a value is an integer.

Determine the specification defined classification of an object.

Type assertions aka less-broken `typeof`

A simple Node.js module to check if a TCP port is already bound.

Hook and modify stdout and stderr

Check if a string is a URL

Check if a string is SVG

Determine a value's type.

Test if a value is a Uint8Array.

Test if a value is a Uint16Array.

Check if a URL is relative

ESLint shareable config for XO

Check if an environment is little endian.

JavaScript Standard Style

Returns true if a file path does not contain any invalid characters.

Determine if a filename and/or buffer is text or binary. Smarter detection than the other solutions.

Check if a binary is working

Check if a string is HTML

maximally minimal type-testing library

Checks if the given value is a window object.

JavaScript/TypeScript linter (ESLint wrapper) with great defaults

ESLint shareable config for the Google style

A simple and composable way to validate data in JavaScript (and TypeScript).

Returns true if the value passed is all whitespace.

JavaScript Standard Style React/JSX support - ESLint Shareable Config

JavaScript Semistandard Style - ESLint Shareable Config

Binary wrapper that makes your programs seamlessly available as local dependencies

Returns `true` if an array has a glob pattern.

Ember CLI addon for detecting missing npm and bower dependencies before executing ember commands

Binary wrapper that makes your programs seamlessly available as local dependencies

`util.inspect` with additional type information

Check if Electron is running in development

Check if a Buffer/Uint8Array is a PNG image

A tiny javascript type testing tool

Check if a string only contains alphanumeric characters

Check if a string is a valid JavaScript identifier

find undeclared identifiers and property accesses in a javascript file.

ESLint shareable config for TypeScript to be used with eslint-config-xo

Check if a Buffer/Uint8Array is a JPEG image

Match BCP 47 language tags with language ranges per RFC 4647

Parse dotenv files for Boolean, Array, and Number variable types, built for CrocodileJS

ESLint shareable config for XO with 2-space indent

Binary wrapper that makes your programs seamlessly available as local dependencies

Ensure a path doesn't contain null bytes

Test if a finite numeric value is an odd number.

Context menu for your Electron app

Checks TypeScript types match expected values

checks whether a hyperlink is alive (200 OK) or dead

Test if a double-precision floating-point numeric value is positive zero.

Check whether a value is "empty".

Test if a finite double-precision floating-point number is an integer.

A proxy to `path`, replacing `\` with `/` for all results

Check if a Buffer/Uint8Array is a GIF image

Validate domain name

Verify if something is a Promise

Robustly checks an array of URLs for liveness.

Checks that given package is installed globally or locally.

Keep watch of your bundle size

Markdown TaskList components

Try to downgrade the permissions of a process with root privileges and block access if it fails

check if an AST node is a function of some sort

Reshape into a better npm audit for the community and encourage more people to include security audit into their process.

Test if a double-precision floating-point numeric value is negative zero.

Get a property from an object using dot (object path) notation.

Test if a finite numeric value is an even number.

Returns true if the given is falsey (according to JavaScript) or matches a 'falsey' keyword.

Detect the audio type of a Buffer/Uint8Array

Detect potential issues with users system that could prevent Yeoman from working correctly

Tiny wrapper around ansi-colors to add colored symbols and a timestamp.

Is this a bluebird promise I see before me?

Utils to deal with TCP ports and hostnames. Safe for everyday use.

Check if a value is a `Blob`

Check if a Buffer/Uint8Array is a TAR file

A gulp plugin for processing files with ESLint

Check if a process is running

Test if a value is NaN.

Is given string a language code (as per IANA)

Promisified version of node-which

Check whether a binary exists in the PATH environment variable

Test if a value is a number having an integer value.

check if the current node version has async_hooks.

Test if a value is a number having a nonnegative integer value.

ESLint shareable config for React to be used with eslint-config-xo

Utilities to get and check variable types (isString, isPlainObject, isRegExp, etc)

Check if browser is Internet Explorer

Check if browser is Firefox

Detect the image type of an ArrayBuffer/Uint8Array

Fully customizable animated bouncy checkbox for React Native

Check whether a package or organization name is available on npm

checks the all of the hyperlinks in a markdown text to determine if they are alive or dead

Async npm module for Node JS that reads the first line of a file

TypeScript Standard Style based on StandardJS

Checks if the given value is null or undefined

Determine if an array or object is equivalent with another, *not* recursively

Aids humans and automation in managing npm audit results

TypeScript / JavaScript library for detect WebAssembly features in node.js & browser

Check if a value is a function

Test if a value is a number having a positive integer value.

Checks if the given value is a native function.

Test if a value is a Uint8ClampedArray.

Test if a value is an Int32Array.

Check the validity of the format of an EU VAT number

Checks if a given object is iterable

A JSON fixer

Test if a value is an Int16Array.

Validate hostname based on RFC-1123

Check if a Buffer/Uint8Array is a ZIP file

Returns `true` if a value exists in the given string, array or object.

Test if a value is a collection.

3x as fast as `is-whitespace` and `whitespace-regex` thanks to `is-string-blank`. This package is a simple function that accepts an argument and returns `true` if it is a string AND it is not blank. Supports Node and Browser environments.

A command line utility to read version from package.json and attach it into your module as a property

Test if an object's own property is enumerable.

$(document).ready() for the 21st century

Test if a value is an Int8Array.

Looks up the first non-whitespace character to the left/right of a given index

A tool to enable the checking, inserting and removal of licenses

A gulp plugin to lint code with ESLint 8 and 9.

Check if a string is an IP address

Test if a value is an arguments object.

Check for outdated, incorrect, and unused dependencies.

Test if a value is array-like.

check if an AST node is a MemberExpression, in general or a specific one

Check if a directory is empty.

Assertions and Validations for TypeScript

A simple CLI to run Node.js and report code coverage.

A TypeScript ESLint config that loves you

is-iojs determines if runtime is io.js.

Test if a value is an array-like object of numbers.

Check if the user is running the latest version of the app

A collection of functions for working with different casings.

Check if the machine is running Windows or not.

Test if a finite double-precision floating-point number is a nonnegative integer.

Compile TypeScript interfaces into a description that allows runtime validation

The module has JS functions to check all imports or required modules and check if the file is a ES Module or a CJS/ JS Module or Script