isarray

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

Node's event emitter for all engines.

node's assert.deepEqual algorithm

Get the first fulfilled promise that satisfies the provided testing function

Browser-friendly inheritance fully compatible with standard node.js inherits()

JWA, JWS, JWE, JWT, JWK, JWKS for Node.js, Browser, Cloudflare Workers, Deno, Bun, and other Web-interoperable runtimes

Lightweight browser detector

LRU and FIFO caches for Client or Server

Browser running for Vitest using your browser of choice

Browser running for Vitest using playwright

Browser running for Vitest using webdriverio

prelude.ls is a functionally oriented utility library. It is powerful and flexible. Almost all of its functions are curried. It is written in, and is the recommended base library for, LiveScript.

Get the first path that exists on disk of multiple paths

Converts a source-map from/to different formats and allows adding/changing properties.

Browser running for Vitest

Robustly `.call.bind()` a function

An AST-based pattern checker for JavaScript.

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

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

The semantic version parser used by npm.

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

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

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

ES6 spec-compliant RegExp.prototype.flags shim.

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

string representations of objects in node and the browser

Is this value a JS SharedArrayBuffer?