#is

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

Check if something is a promise

utility to check if a node is a (certain) element

ES6-compliant shim for Number.isNaN - the global isNaN returns false positives.

Is this value a `document.all`, eg, an object with the [IsHTMMLDDA]] internal slot?

If you use globs, this will make your code faster. 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 better user experience. 55+ million downloads.

Check if a project is using Yarn

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

ES6-compliant shim for Object.is - differentiates between -0 and +0, and can compare to NaN.

Is this value a JS FinalizationRegistry? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

Is this value a JS Map? This module works cross-realm/iframe, and despite %Symbol.toStringTag%.

Is this value a JS SharedArrayBuffer? This module works cross-realm/iframe, does not depend on `instanceof` or mutable properties, and despite ES6 Symbol.toStringTag.

Is this value a JS WeakMap? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

Check if the process is running inside a Docker container

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

Check if a file path is a binary file

Isomorphic, functional type-checking for Javascript

Check if a value is a regular expression

Check if something is a Node.js stream

Check if a file path is a text file

Check if an object can be used like an Array

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Returns `true` if a file path appears to be relative. Moved from the "relative" lib.

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

Check if a value is an object

Check if the process is running inside a container (Docker/Podman)

Check if your code is running as an npm or yarn script

Check if a value is a plain object

Returns true if a filepath is absolute. The original path-is-absolute.

Check if something is a generator function