inspect-js/is-core-module

Is this specifier a node.js core module?

syntax-tree/unist-util-is

utility to check if a node passes a test

sindresorhus/is-stream

Check if something is a Node.js stream

juliangruber/isarray

Array#isArray for older browsers.

juliangruber/builtins

List of node.js builtin modules

tarruda/has

Object.prototype.hasOwnProperty

isaacs/readable-stream

Node-core streams for userland

es-shims/object-is

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