JSPM

Style elements relative to other elements in CSS

ES2015 `Array#findIndex()` ponyfill

A pseudo-class for matching elements in a selector list

A tiny, zero-dependency yet spec-compliant asynchronous iterator polyfill/ponyfill for ReadableStreams.

Polyfill crypto.randomUUID

Use the :dir pseudo-class in CSS

Bare minimum fetch polyfill in 500 bytes

Polyfills the ResizeObserver API and supports box size options from the latest spec

This is a polyfill for Buffer#indexOf introduced in NodeJS 4.0.

is that thing a function? Use this module to find out

ES2017 spec-compliant String.prototype.padEnd shim.

backwards compatible version of builtin events.listenercount

Performance timer based on performance.mark() and measure()

An ES5 spec-compliant `Array.prototype.map` shim/polyfill/replacement that works as far down as ES3.

Polyfills for React Native.

Ponyfill for upcoming Element.scrollIntoView() APIs like scrollMode: if-needed, behavior: smooth and block: center

Minimal zero-dependency utilities for using JavaScript Iterables in all environments.

Simple setImmediate shim

Array.prototype.find ES6 polyfill.

ECMAScript6 Map polyfill

Error.captureStackTrace ponyfill

ES spec-compliant shim for TypedArray.prototype.slice

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

A ponyfill for the ES 2015 (ES6) `Array.from()`.

Common layer to be used by crypto libraries based on WebCrypto API for input validation.

Polyfill exporting trevnorris's 0.11+ asyncListener API.

ECMAScript 2015 (ES6) Object.assign polyfill and ponyfill

Fork of eventsource package - W3C compliant EventSource client for Node.js and browser (polyfill)

A BroadcastChannel that works in New Browsers, Old Browsers, WebWorkers, NodeJs, Deno and iframes

Polyfill for the Encoding Living Standard's API.

Support any Observable library and polyfill

A robust & optimized `String.fromCodePoint` polyfill, based on the ECMAScript 6 specification.

ES Proposal spec-compliant shim for AggregateError

ES Proposal spec-compliant shim for Promise.allSettled

Polyfill Node.js core modules in Webpack.

Polyfill for the proposed React context API

An ES5 spec-compliant `Array.prototype.filter` shim/polyfill/replacement that works as far down as ES3.

Path2D API for node. Can be used for server-side rendering with canvas

Polyfill for: https://tc39.es/proposal-intl-displaynames

A cross platform Promise.allSettled polyfill

ES Proposal spec-compliant shim for Promise.prototype.finally

ECMAScript 5 compatibility shims for legacy JavaScript engines

ES2019 spec-compliant String.prototype.trimLeft shim.

ES2017 spec-compliant String.prototype.padStart shim.

Spec-compliant shim for Symbol.prototype.description proposal.

A small implementation of `crypto.getRandomValues` for React Native. This is useful to polyfill for libraries like [uuid](https://www.npmjs.com/package/uuid) that depend on it.

ES2019 spec-compliant String.prototype.trimLeft shim.

A lightweight and trustworthy URL polyfill for React Native

ES2015 spec-compliant shim for Reflect.ownKeys

Polyfill for the proposed React context API

ES6 Array.find ponyfill. Return the first array element which satisfies a testing function.

Polyfills Path2D api for canvas rendering

Fake IndexedDB: a pure JS in-memory implementation of the IndexedDB API

A ponyfill (doesn't overwrite the native methods) to use Edge Runtime APIs in any environment.

A robust & optimized `String.prototype.codePointAt` polyfill, based on the ECMAScript 6 specification.

The fastest smallest Javascript polyfill for the encode of TextEncoder and decode of TextDecoder for UTF-8 only. Made by AnonyCo with ❤️ from 🐕s.

finds an item in an array matching a predicate function, and returns its index

A polyfill for http://www.w3.org/TR/eventsource/

Polyfill the ECMA-402 Intl API (except collation)

An ESnext spec-compliant shim/polyfill/replacement for all Well-Known Symbols that works in any environment with Symbols.

Smooth Scroll behavior polyfill

Ensure a path doesn't contain null bytes

a simple polyfill for javascript URLSearchParams

ES2015 (ES6) Number.isInteger polyfill

Polyfill/shim for `document.contains`

Text Decoder

Comprehensive TypeScript/JavaScript utility library with cross-environment support (Node.js, browser, web worker) providing helper functions, polyfills (ES5-ES2023), type checking utilities, and optimized implementations for better minification and code r

EventSource polyfill for browser and node.js

Return the prototype of a provided object.

Cross-browser JavaScript shim that fully implements element.classList (referenced on MDN)

ECMAScript6 WeakMap polyfill

A polyfill for creating CustomEvents on IE9+ if the native implementation is missing.

Ponyfill for ES2020 Intl.NumberFormat

Intl.MessageFormat / Unicode MessageFormat 2 parser, runtime and polyfill

Polyfill for Intl.PluralRules

Test whether a path exists on the filesystem.

Polyfill for perf_hooks.monitorEventLoopDelay(...)

Polyfills nodejs builtin modules and globals for the browser.

Blob.js implements the W3C Blob interface in browsers that do not natively support it.

A browser polyfill for W3C EventSource (http://www.w3.org/TR/eventsource/)

Mouse state change listener

Cross browser mouse event property access

JavaScript implementation of the Web Animations API

Intl.DateTimeFormat polyfill

A Javascript polyfill for browsers that don't support the object-fit CSS property

Polyfill for Scoped CSS

The URLSearchParams polyfill.

HTML Custom Elements Polyfill

An implementation and polyfill of the Resize Observer draft.

Web Components Polyfills

An ES5 spec-compliant `Array.prototype.every` shim/polyfill/replacement that works as far down as ES3.

Return the closest element matching a selector up the DOM tree

Promise.witResolvers() polyfill

A polyfill for the asynchronous clipboard API

WebGL2 API Polyfills for WebGL1 WebGLRenderingContext

A polyfill for the encryptionScheme field in EME

ES 2021 spec-compliant shim for Promise.any

Client-side support for CSS custom properties (aka "CSS variables") in legacy and modern browsers

A robust ES3-compatible polyfill for the `RegExp.escape` proposal - see https://github.com/tc39/proposal-regex-escaping

Constructible style sheets/adopted style sheets polyfill

A BroadcastChannel that works in New Browsers, Old Browsers, WebWorkers

Ponyfill for smooth scrolling elements into view (if needed!)

Wrapper for the Page Visibility API

A polyfill for the proposed inert API

A Barcode Detection API polyfill that uses ZXing webassembly under the hood

Polyfill for the Proxy object

Polyfill object-fit and object-position on images on IE9, IE10, IE11, Edge, Safari, ...

Deno namespace shim for Node.js

Polyfill for navigator.sendBeacon()

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

Polyfill for RFC 566: @cached

An ES-spec-compliant (proposed) Array.prototype.at shim/polyfill/replacement that works as far down as ES3

Polyfill for RFC 580: Destroyables

A fork of create-react-context in MIT license

Polyfill for the basic functionality of `Function.name` accessor property in its pre-ES6 form

An ES5 mostly-spec-compliant `Object.getPrototypeOf` sham/polyfill/replacement that works in as many engines as possible

polyfill for `KeyboardEvent.prototype.key`

A polyfill for Ember CLI's TypeScript blueprint capabilities.

Javascript Error Polyfill

A robust & optimized `String.prototype.startsWith` polyfill, based on the ECMAScript 6 specification.

A polyfill for the Record and Tuple Stage 2 ECMAScript proposal.

A cross browser solution to scrolling during drag and drop.

This package includes the [core-js](https://github.com/zloirock/core-js) polyfill for `String#replaceAll`, along with TypeScript typings.

Polyfill requestAnimationFrame and cancelAnimationFrame

Popover Attribute Polyfill

Smooth Scroll behavior polyfill

MediaRecorder polyfill to record audio in Edge and Safari

A Javascript utility library for working with native objects.

A polyfill for the element internals specification

PostCSS plugin for Flexibility polyfill

JavaScript polyfill for the WHATWG spec of focusOptions, that enables a set of options to be passed to the focus method.

CSSOM-valid and jsdom/Jest-compatible matchMedia polyfill for server-side unit tests

A polyfill for Ember.assign in <= 2.4

CanvasRenderingContext2D.roundRect() and Path2D.roundRect() polyfill

Standard library

Transit is a data format and a set of libraries for conveying values between applications written in different languages. This library provides support for marshalling Transit data to/from Javascript.

A JavaScript polyfill for Flexbox

MDN polyfills

Polyfill for ES6 Promise

Super small `Element.matches` fix for older browsers (IE 9+, Edge 12+, Safari, Android browsers)

A polyfill for crypto.randomFill and crypto.randomFillSync from Node.js core

ECMAScript 7 compatibility shims for legacy JavaScript engines

A polyfill for the 'scroll-behavior' CSS-property

A minimal polyfill for Element.closest

Returns the first index at which a given element can be found.

Quick wrapper that finds TextDecoder or polyfills a bad implementation

Polyfill for CSS `position: sticky`

<form>.requestSubmit() polyfill

Replaces `arr.includes(val)' with `arr.indexOf(val) >= 0`.

Polyfill for making HTML5 drag and drop possible in all browsers.

W3C's Fullscreen API Polyfill

Node's util.inspect, extracted for use on the Web

Return the first index at which a given element can be found.

Round a double-precision floating-point number toward zero.

User Timing polyfill

Simple ES6 Object.assign() polyfill for older environments.

Browser polyfill for making React Native compatible with web libs like pixi.js, three.js, phaser.js

A polyfill that fetches external SVGs referenced in use elements when the browser itself fails to do so.

Provide helpers that polyfill all methods defined in [iterator helpers proposal](https://github.com/tc39/proposal-iterator-helpers), both for `Iterator` and `AsyncIterator`, and even more.

A robust & optimized `String.prototype.endsWith` polyfill, based on the ECMAScript 6 specification.

All inclusive customElements polyfill for every browser

WebAssembly interpreter

A polyfill for the Resize Observer API

`Object.entries()` ponyfill

An ES-spec-compliant shim/polyfill/replacement for the `.cause` property on all Error types that works as far down as ES3

Validate your forms, frontend, without writing a single line of javascript!

Polyfill/shim for stream.finished in node versions < v10

Scoped CustomElementRegistry Polyfill

An EventTarget polyfill

HTML <details> element polyfill

Runtime polyfills for TypeScript libs, powered by core-js!

A polyfill for the native import() in the browser

Polyfill for the proposed CSS anchor positioning spec

Compatibility layer for efficient streaming of binary data using [WHATWG Streams](https://streams.spec.whatwg.org/)

React component for anchor links using the smoothscroll polyfill.

Polyfill/shim for stream.pipeline in node versions < v10

Object.fromEntries() polyfill

An ES-spec-compliant Set shim/polyfill/replacement that works as far down as ES3

An ESnext spec-compliant `DisposableStack`, `AsyncDisposableStack`, `Symbol.dispose`, and `Symbol.asyncDispose` shim/polyfill/replacement that works as far down as ES3.

Object.setPrototypeOf Polyfill

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

Patches global.Promise to use bluebird and returns a bluebird instance

fs.promises polyfill

Tiny Web Share API Wrapper with fallback for unsupported browsers

ES Proposal spec-compliant shim for SuppressedError

An ES-spec-compliant Map shim/polyfill/replacement that works as far down as ES3

A browser polyfill for W3C EventSource (http://www.w3.org/TR/eventsource/)

A cross browser solution to scrolling during drag and drop.

Cross-browser implementation of W3C saveAs API

A polyfill of IntersectionObserver API

Standardizer for node's console.assert

polyfill for es8 Object.values

Polyfills and patches missing or partially supported web and core APIs

ECMAScript Map like object.

Polyfills the a[download] attribute

The minimal set of polyfills that the Aurelia platform needs to run on ES5 browsers.

Compute the arcsine of a double-precision floating-point number.

Polyfill for scrollend event

An ES5 spec-compliant `Array.prototype.some` shim/polyfill/replacement that works as far down as ES3.

Determines whether a string ends with the characters of another string.

get-own-property-symbols ========================

Simple, small and fast jQuery polyfill for the HTML5 <input type="range"> slider element

Polyfill Web Speech API with Cognitive Services Speech-to-Text service

TypeScript shim for DOMMatrix

Polyfill for BroadcastChannel for Safari, old Chrome and Opera

A polyfill for the proposed blocking elements stack API

A canvas.toBlob() implementation

PostCSS plugin that updates the standard object-fit tag to work with the object-fit-images polyfill for browsers that do not natively support object-fit.

Run ES Module syntax in any browser – even IE!

Polyfill to provide array.find on IE.

A fully spec-compliant polyfill for 'Intl.ListFormat'

Compute the arccosine of a double-precision floating-point number.

High performance WebRTC polyfill for Node.JS via libdatachannel using Node Native/NAPI.

An accessible polyfill for `[input type='time']` elements modeled after the Chrome & Firefox desktop implementations.

A jquery polyfill for the old, removed $.live() method

React.createRef() polyfill

Small vanilla javascript that feature detect the :focus-within pseudo selector and polyfills it with a standard css class if necessary.

An trim polyfill for legacy browsers.

An essential WeakMap polyfill for legacy browsers.

Polyfill for the HTML5 `<details>` element

console.time, console.timeLog and console.timeEnd polyfill for react-native

An Object.fromEntries polyfill

Return elements matching a selector relative to the current node

Cross-platform Blob implementation for NodeJS and the Web.

Plugin for injecting a polyfills loader to HTML pages

Polyfill for SVG 2 getPathData() and setPathData() methods

CSS.supports() shim

Simple polyfill for the NodeList.forEach method.

A polyfill for the Cookie Store API

Canvas toBlob polyfill

An importNode polyfill for IE11 and other legacy browsers

W3C compliant EventSource client for Node.js and browser (polyfill)

A minimal polyfill for Element scroll extensions.

`core-js`'s `web/url.js` prebundled for the browser

Ember cli addon that includes a polyfill for closest() if needed.

ES2015 WeakMap polyfill for Ember.WeakMap

A simple SDP interoperability layer for Unified Plan/Plan B

Shadow DOM polyfill

Tiny KeyboardEvent#key shim for IE and MS Edge

Web Streams, based on the WHATWG spec reference implementation

html5 storage interface for node and browser

A polyfill for missing Object.values / Object.entries

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

A small mostly spec. compliant polyfill/ponyfill for SharedWorkers, it acts as a drop in replacement for normal Workers, and supports an API surface that matches normal Workers.

ARIA element reflection polyfill for strings

Polyfill for Function.prototype.bind

Development server for modern web apps

<h1 align="center" style="border-bottom: none;">🔎 PerformanceObserver Polyfill</h1> <p align="center"> <a href="https://travis-ci.org/fastly/performance-observer-polyfill"> <img alt="Travis" src="https://img.shields.io/travis/fastly/performance-obs

This fork provide the following on top of the original:

ES6 Map Implemented in TypeScript