the definitive JavaScript type testing library

Check if something is a Node.js stream

Is this value an ES BigInt?

Check if stdout or stderr is interactive

Check if a value is an object

Is this value a JS ArrayBuffer?

Check if the process is running inside a Docker container

Determine if a value is an ES6 Symbol or not.

Check if a character is alphanumerical

Check if a value is a plain object

Check if a character is hexadecimal

Check if a character is alphabetical

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

Check if something is a generator function

Is this value a JS SharedArrayBuffer?

Node is running but you don't know why? why-is-node-running is here to help you.

Check if a value is a regular expression

Check if a character is decimal

Check if a file path is a binary file

Is this specifier a node.js core module?