ECMAScript “ToPrimitive” algorithm. Provides ES5 and ES2015 versions.

Is this value an ES BigInt?

Which kind of Collection (Map, Set, WeakMap, WeakSet) is this JavaScript value? Works cross-realm, without `instanceof`, and despite Symbol.toStringTag.

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

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

ES proposal-spec-compliant Object.fromEntries shim.

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

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

Property based testing framework for JavaScript (like QuickCheck)

Simple to use, blazing fast and thoroughly tested websocket client and server for Node.js

An ES7/ES2016 spec-compliant `Array.prototype.includes` shim/polyfill/replacement that works as far down as ES3.

Encode FormData content into the multipart/form-data format

ES2017 spec-compliant Object.values shim.

Helper functions for V8 coverage files.

Determine if a function is a native async function.

Fire events the same way the user does

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

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

Syntax highlighting with language autodetection.

Pure random number generator written in TypeScript