JSPM

Checks if package-lock.json is Up To Date (= UTD)

Test if a value is a Date object.

Check empty for: array, string, object, function, number, date

Check if a date is valid or not.

Checks if your NPM or Bower dependencies are out of date.

Type assertions aka less-broken `typeof`

Get the native type of a value.

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

Check if a date is invalid or not.

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

Check for outdated, incorrect, and unused dependencies.

Check if argv has a specific flag

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

Check if something is a Node.js stream

Validates if a value is a Date object.

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

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

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

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

Returns true if a string has an extglob.

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

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.

Check if a file path is a binary file

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

Detect whether the terminal supports Unicode

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

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

Check if something is a generator function

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

unist utility to check if a node passes a test

unist utility to recursively walk over nodes, with ancestral information

Type check values

Check if your package was installed globally

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

Runtime library to validate data against TypeScript interfaces

Lint files staged by git

Check if a path is the current working directory

Standard assertion utilities.

micromark extension to support GFM task list items

Check if a value is a regular expression

Check if your code is running as an npm script

Check if something is a promise

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

mdast extension to parse and serialize GFM task list items

Isomorphic, functional type-checking for Javascript

Check if a file path is a text file

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

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

Check if a URL is absolute

Update notifications for your CLI app

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 path is in the current working directory

Check if a value is a Fetch network error

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

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

Returns `true` if the value is a primitive.

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

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

JavaScript Standard Style - ESLint Shareable Config

Check if a value is a natural number

Typescript-compatible minimalistic shallow equality check for arrays/objects

Check if a module ID is resolvable with require()

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

URI validation functions

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

Check if a Buffer/Uint8Array is a GZIP file

Small script to know if a business/service is open or closed from a date using cron definition

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 number is a redirect HTTP status code

A straightforward implementation of base58-check encoding

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

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

Get the operating system CPU architecture

Returns true if a windows file path has invalid characters.

Check if a local or remote port is reachable

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

Check if a string is a URL

Check if a string is SVG

Build a navigation structure programatically

Build templates for initial values

Detect the archive type of a Buffer/Uint8Array

Check if a value is an Observable

Hook and modify stdout and stderr

Check if a binary is working

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

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

`util.inspect` with additional type information

hast utility to check if a node has a property

Detect the archive type of a Buffer/Uint8Array

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

Binary wrapper that makes your programs seamlessly available as local dependencies

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

Validates if a value is an array.

Match BCP 47 language tags with language ranges per RFC 4647

A lean, zero dependency library to provide a useful base for your project. Checksums, cryptography, codecs, date-times, error-checking-codes, logging, pseudorandom number generation. The tools you need for any project. Secure build pipeline, provenance

Check if a string is an IP address

Function argument validation for humans

Check if a binary is working

Validates if a value is a number.

A lean, zero dependency library to provide a useful base for your project. Checksums, cryptography, codecs, date-times, error-checking-codes, logging, pseudorandom number generation. The tools you need for any project. Secure build pipeline, provenance

Check dependencies in your node module

Returns true if the value passed is all whitespace.

Checks if the given value is a window object.

My incredible module

Validates if a value is an integer.

Check if a string only contains alphanumeric characters

Check if a Buffer/Uint8Array is a PNG image

A tiny javascript type testing tool

find undeclared identifiers and property accesses in a javascript file.

JavaScript Standard Style JSX support - ESLint Shareable Config

Binary wrapper that makes your programs seamlessly available as local dependencies

Test if a value is an array-like object containing only Date objects.

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

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

Check whether a value is "empty".

A lean, zero dependency library to provide a useful base for your project. Checksums, cryptography, codecs, date-times, error-checking-codes, logging, pseudorandom number generation. The tools you need for any project. Secure build pipeline, provenance

A lean, zero dependency library to provide a useful base for your project. Checksums, cryptography, codecs, date-times, error-checking-codes, logging, pseudorandom number generation. The tools you need for any project. Secure build pipeline, provenance

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

Check if mobile browser.

Ensure a path doesn't contain null bytes

Check if a Buffer/Uint8Array is a JPEG image

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

Binary wrapper for Flow - A static type checker for JavaScript

Check whether a RegExp flag is supported

Binary wrapper that makes your programs seamlessly available as local dependencies

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.

Check if a Buffer/Uint8Array is a GIF image

JavaScript Standard Style

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

Test if an object has a specified property.

Validate domain name

Test if a value is a string.

Test if a value is object-like.

Test if a value is a function.

Test if a value is a Float64Array.

maximally minimal type-testing library

Check if an environment is big endian.

Test if a value is a boolean.

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

Test if a value is a Float32Array.

Test if a value is a number.

Test if a value is a Uint32Array.

Test if a value is an object.

ESLint shareable config for the Google style

Check if a string is HTML

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

Test if a value is a Buffer object.

Check if a URL is relative

Test if a value is a regular expression.

Check TypeScript type definitions

Test if a value is a plain object.

Test if a value is a regular expression string.

Test whether a path exists on the filesystem.

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

Check if a Buffer/Uint8Array is a TAR file

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

Determine the specification defined classification of an object.

ESLint shareable config for XO

Determine a value's type.

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

Test if a value is a Uint8Array.

Test if a value is a Uint16Array.

Check if the current Linux session is using Wayland

Check if browser is Firefox

Is this a bluebird promise I see before me?

check if an AST node is a function of some sort

Check if an environment is little endian.

Check if a value is a `Blob`

Check if browser is Internet Explorer

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

JavaScript/TypeScript linter (ESLint wrapper) with great defaults

Check if Electron is running in development

Simple, TypeScript zero-dependency environment validation/initialization tool.

check if the current node version has async_hooks.

Promisified version of node-which

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

Is given string a language code (as per IANA)

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

Check if a process is running

Check whether a binary exists in the PATH environment variable

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

Check if the process is running in an SSH session

Checks TypeScript types match expected values

Check if a value is a function

Checks if the given value is null or undefined

Check if a string is a valid JavaScript identifier

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 gulp plugin for processing files with ESLint

Verify if something is a Promise

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

Checks if the given value is a native function.

Check whether a package or organization name is available on npm

🔌 CLI to check/generate .env files and maintain them synchronized

Check if a string is an IP address

Check if a Buffer/Uint8Array is a ZIP file

A JSON fixer

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

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

Keep watch of your bundle size

Context menu for your Electron app

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

Detect the image type of an ArrayBuffer/Uint8Array

Detect the audio type of a Buffer/Uint8Array

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

JavaScript Standard Style React/JSX support - ESLint Shareable Config

Check if the machine is running Windows or not.

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

A TypeScript ESLint config that loves you

Checks if a given object is iterable

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

Test if a finite numeric value is an odd number.

Check if a Buffer/Uint8Array is a BZIP2 file

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

Check if a directory is empty.

ESLint shareable config for XO with 2-space indent

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

JavaScript Semistandard Style - ESLint Shareable Config

Check if a value is undefined or not.

Validates password according to flexible and intuitive specifications

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

Detect the appearance of an element in the browser DOM

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

Keep your library size in check

Node.js utility tool for creating and checking subresource integrity

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

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

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

Test if two values are both Date objects corresponding to the same date and time.

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

Check the validity of the format of an EU VAT number

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Check if an object is an array or a typed array

Aids humans and automation in managing npm audit results

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

Test if a finite numeric value is an even number.

A collection of functions for working with different casings.

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

Checks that given package is installed globally or locally.

Validate hostname based on RFC-1123

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