call-bind

node's assert.deepEqual algorithm

ES6 spec-compliant RegExp.prototype.flags shim.

ES2015-compliant shim for Object.is - differentiates between -0 and +0

Get an iterator for any JS language value. Works robustly across all environments, all versions.

Set a function's length property

Robust call-bound JavaScript intrinsics, using `call-bind` and `get-intrinsic`.

Get and robustly cache all JS language-level intrinsics at first require time

Set a function's length property

`Object.defineProperty`, but not IE 8's broken one.

An Esprima-compatible JavaScript parser built on Acorn

A query library for ECMAScript AST using a CSS selector like query language.

A JavaScript parser

A simple cache for a few of the JS Error constructors.

A robust, ES3 compatible, "has own property" predicate.

An AST-based pattern checker for JavaScript.

Determine if the JS environment has `Symbol.toStringTag` support. Supports spec, or shams.

Implementation of Function.prototype.bind

An AST-based pattern checker for JavaScript.

Get and robustly cache all JS language-level intrinsics at first require time

string representations of objects in node and the browser

Is this an arguments object? It's a harder question than you think.

Does this JS environment support the `name` property on functions?

A simple cache for a few of the JS Error constructors.

Array#isArray for older browsers

`Object.getOwnPropertyDescriptor`, but accounts for IE's broken implementation.

The semantic version parser used by npm.

Store information about any JS value in a side channel. Uses WeakMap if available.

Get the byte length of an ArrayBuffer, even in engines without a `.byteLength` method.

Is this value a JS regex? Works cross-realm/iframe, and despite ES6 @@toStringTag