A library for obtaining browser versions with their maximum supported Baseline feature set and Widely Available status.

A light-weight module that brings Fetch API to node.js

Is this specifier a node.js core module?

Simple and complete DOM testing utilities that encourage good testing practices.

ES6 spec-compliant RegExp.prototype.flags shim.

The `postinstall` script helper for handling native bindings in legacy `npm` versions

Define multiple non-enumerable properties at once. Uses `Object.defineProperty` when available; falls back to standard assignment in older engines.

An ES2015 mostly-spec-compliant `Reflect.getPrototypeOf` sham/polyfill/replacement that works in as many engines as possible

An ES2019 spec-compliant `Array.prototype.flatMap` shim/polyfill/replacement that works as far down as ES3.

TypeScript-first schema declaration and validation library with static type inference

ES6 spec-compliant Object.assign shim. From https://github.com/es-shims/es6-shim

Custom jest matchers to test the state of the DOM

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

Returns an array of Typed Array names that are available in the current environment

A querystring parser that supports nesting and arrays, with a depth limit

Determine if a function is a native generator function.

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

ES spec-like internal slots

A pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module.

Gets the description of a Symbol. Handles `Symbol()` vs `Symbol('')` properly when possible.