JSPM

Check if argv has a specific flag

Get the native type of a value.

Check if something is a Node.js stream

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

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

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

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

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 the value is an object and not an array or null.

Returns true if a string has an extglob.

Check if a file path is a binary file

Check if a value is a plain object

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

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

Check if something is a generator function

Detect whether the terminal supports Unicode

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

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

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

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

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 if a value is an object

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

Detect whether a terminal supports hyperlinks

Type check values

unist utility to recursively walk over nodes, with ancestral information

unist utility to check if a node passes a test

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

Check if your package was installed globally

Runtime library to validate data against TypeScript interfaces

Check if a path is the current working directory

Lint files staged by git

Check if your code is running as an npm script

micromark extension to support GFM task list items

Check if a value is a regular expression

Isomorphic, functional type-checking for Javascript

Check if something is a promise

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

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

Check if a URL is absolute

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

Check if a file path is a text file

Update notifications for your CLI app

Check if a path is in the current working directory

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`.

mdast extension to parse and serialize GFM task list items

Check if a value is a Fetch network error

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

JavaScript Standard Style - ESLint Shareable Config

Check if a value is a natural number

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

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

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

Returns `true` if the value is a primitive.

Check if a Buffer/Uint8Array is a GZIP file

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

Check if a module ID is resolvable with require()

Check if a number is a redirect HTTP status code

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

Typescript-compatible minimalistic shallow equality check for arrays/objects

Returns true if a windows file path has invalid characters.

URI validation functions

A straightforward implementation of base58-check encoding

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

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 string is a URL

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

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

Check if a value is an Observable

Get the operating system CPU architecture

Detect the archive type of a Buffer/Uint8Array

Check if a string is SVG

Check if a local or remote port is reachable

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

Binary wrapper that makes your programs seamlessly available as local dependencies

Hook and modify stdout and stderr

Check if a binary is working

Type assertions aka less-broken `typeof`

hast utility to check if a node has a property

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

Detect the archive type of a Buffer/Uint8Array

`util.inspect` with additional type information

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

Check if a binary is working

Validates if a value is an array.

Check if a string is an IP address

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

Validates if a value is a number.

JavaScript Standard Style JSX support - ESLint Shareable Config

A tiny javascript type testing tool

Match BCP 47 language tags with language ranges per RFC 4647

Function argument validation for humans

Check dependencies in your node module

Checks if the given value is a window object.

Binary wrapper that makes your programs seamlessly available as local dependencies

Returns true if the value passed is all whitespace.

Validates if a value is an integer.

Check if a Buffer/Uint8Array is a PNG image

Check if a string only contains alphanumeric characters

find undeclared identifiers and property accesses in a javascript file.

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

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

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

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

Binary wrapper that makes your programs seamlessly available as local dependencies

Binary wrapper for Flow - A static type checker for JavaScript

Ensure a path doesn't contain null bytes

Check whether a value is "empty".

Check if a Buffer/Uint8Array is a JPEG image

JavaScript Standard Style

Check if mobile browser.

Test if an object has a specified property.

Validate domain name

Check whether a RegExp flag is supported

Check if a Buffer/Uint8Array is a GIF image

Test if a value is an array.

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

Determine the name of a value's constructor.

Test if a value is object-like.

Check if an environment is big endian.

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

ESLint shareable config for the Google style

Test if a value is a regular expression string.

Test if a value is a string.

Check if a string is HTML

Check if a URL is relative

Test if a value is a boolean.

Test if a value is a function.

maximally minimal type-testing library

Test if a value is a Float64Array.

ESLint shareable config for XO

Test if a value is a Uint32Array.

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

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

Check for outdated, incorrect, and unused dependencies.

Test if a value is an object.

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

Test if a value is a Float32Array.

Test if a value is a number.

JavaScript/TypeScript linter (ESLint wrapper) with great defaults

check if an AST node is a function of some sort

Test if a value is a Buffer object.

Test if a value is a regular expression.

Check TypeScript type definitions

Test whether a path exists on the filesystem.

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

Test if a value is a plain object.

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

Determine the specification defined classification of an object.

Check if a Buffer/Uint8Array is a TAR file

Determine a value's type.

Is this a bluebird promise I see before me?

Test if a value is a Uint8Array.

Test if a value is a Uint16Array.

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

Check if an environment is little endian.

Check if a value is a `Blob`

Check if browser is Firefox

Check if browser is Internet Explorer

Check if a process is running

Check whether a binary exists in the PATH environment variable

Promisified version of node-which

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

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

Check if Electron is running in development

Detect the audio type of a Buffer/Uint8Array

Verify if something is a Promise

Is given string a language code (as per IANA)

check if the current node version has async_hooks.

Checks if the given value is null or undefined

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

Checks if a given object is iterable

Checks TypeScript types match expected values

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

Check whether a package or organization name is available on npm

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

Checks if the given value is a native function.

Check if a string is a valid JavaScript identifier

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

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

Check if a string is an IP address

A gulp plugin for processing files with ESLint

Keep watch of your bundle size

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.

JavaScript Standard Style React/JSX support - ESLint Shareable Config

Check if a Buffer/Uint8Array is a ZIP file

A JSON fixer

Check if a directory is empty.

A TypeScript ESLint config that loves you

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

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

Detect the image type of an ArrayBuffer/Uint8Array

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

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

JavaScript Semistandard Style - ESLint Shareable Config

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

Check if a value is a function

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

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

ESLint shareable config for XO with 2-space indent

Check if a Buffer/Uint8Array is a BZIP2 file

Validates password according to flexible and intuitive specifications

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

Test if a finite numeric value is an odd number.

is-iojs determines if runtime is io.js.

Keep your library size in check

Check if a string is a valid filename

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

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

Returns true if an object has an own, nested property using dot notation paths ('a.b.c').

Check the validity of the format of an EU VAT number

A collection of functions for working with different casings.

Context menu for your Electron app

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

Aids humans and automation in managing npm audit results

Check if the machine is running Windows or not.

Check whether a binary version satisfies a semver range

Check if an object is an array or a typed array

Validate hostname based on RFC-1123

Test if a value is NaN.

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

TypeScript Standard Style based on StandardJS

Markdown TaskList components

Hunspell compatible spell checker

Check if the package is being installed by another package

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

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

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

Check if the process is running as administrator on Windows

Check if a value is undefined or not.

Test if a value is a Uint8ClampedArray.

Test if a value is an Int16Array.

Test if a value is an Int32Array.

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

Detect the appearance of an element in the browser DOM

Test if a finite numeric value is an even number.

Checks that given package is installed globally or locally.

Test if an object's own property is enumerable.

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

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

Returns true if the current node version matches the given semver expression

Assert a given object is a valid glob option

All the goodness of `feross/standard` with semicolons sprinkled on top.

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

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

Test if a value is a collection.

Test if a value is an Int8Array.

Test if a value is an arguments object.

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