Polyfills and shims

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• promise.prototype.finallyES Proposal spec-compliant shim for Promise.prototype.finally
• smoothscroll-polyfillSmooth Scroll behavior polyfill
• @hypnosphi/create-react-contextPolyfill for the proposed React context API
• well-known-symbolsAn ESnext spec-compliant shim/polyfill/replacement for all Well-Known Symbols that works in any environment with Symbols.
• imscRenders IMSC documents to HTML5 fragments
• @deno/shim-denoDeno namespace shim for Node.js
• @deno/shim-deno-testDeno.test only shim.
• minimal-polyfillsAn ultra light-weight, nonexhaustive, polyfills library
• is-integerES2015 (ES6) Number.isInteger polyfill
• fs-accessNode.js 0.12 fs.access() & fs.accessSync() ponyfill
• url-search-params-polyfilla simple polyfill for javascript URLSearchParams
• null-checkEnsure a path doesn't contain null bytes
• @formatjs/intl-pluralrulesPolyfill for Intl.PluralRules
• symbol.prototype.descriptionSpec-compliant shim for Symbol.prototype.description proposal.
• airbnb-js-shimsJS language shims used by Airbnb.
• reflect.ownkeysES2015 spec-compliant shim for Reflect.ownKeys
• headers-utilsA Headers class polyfill and transformation library.
• url-polyfillPolyfill URL and URLSearchParams
• dc-browserBrowser polyfill for Node.js diagnostics_channel
• @stdlib/fs-existsTest whether a path exists on the filesystem.
• array-findES6 Array.find ponyfill. Return the first array element which satisfies a testing function.
• intlPolyfill the ECMA-402 Intl API (except collation)
• math-log2ES2015 Math.log2() ponyfill
• standardized-audio-contextA cross-browser wrapper for the Web Audio API which aims to closely follow the standard.
• regexp.escapeA robust ES3-compatible polyfill for the `RegExp.escape` proposal - see https://github.com/tc39/proposal-regex-escaping
• number-is-integerES2015 Number.isInteger() ponyfill
• core-assertNode.js `assert` as a standalone module
• buf-compareNode.js `Buffer.compare()` ponyfill
• deep-strict-equalTest for deep equality - Node.js `assert.deepStrictEqual()` algorithm as a standalone module
• custom-event-polyfillA polyfill for creating CustomEvents on IE9+ if the native implementation is missing.
• dommatrixES6+ shim for DOMMatrix
• url-extrasBrowser-compatible implementations of some of Node.js' URL utilities
• @webcomponents/custom-elementsHTML Custom Elements Polyfill
• canvas-roundrect-polyfillCanvasRenderingContext2D.roundRect() and Path2D.roundRect() polyfill
• @formatjs/intl-numberformatPonyfill for ES2020 Intl.NumberFormat
• fetch-jsonpFetch JSONP like a boss using Fetch API
• document.containsPolyfill/shim for `document.contains`
• array.prototype.atAn ES-spec-compliant (proposed) Array.prototype.at shim/polyfill/replacement that works as far down as ES3
• esbuild-plugins-node-modules-polyfillPolyfills nodejs builtin modules and globals for the browser.
• array.prototype.everyAn ES5 spec-compliant `Array.prototype.every` shim/polyfill/replacement that works as far down as ES3.
• node-status-codesNode.js `http.STATUS_CODES` ponyfill
• mouse-eventCross browser mouse event property access
• mouse-changeMouse state change listener
• messageformatIntl.MessageFormat / Unicode MessageFormat 2 parser, runtime and polyfill
• monitor-event-loop-delayPolyfill for perf_hooks.monitorEventLoopDelay(...)
• shallow-clone-shimShallow clones an object while respecting the original property descriptors
• classlist-polyfillCross-browser JavaScript shim that fully implements element.classList (referenced on MDN)
• blob-polyfillBlob.js implements the W3C Blob interface in browsers that do not natively support it.
• es-setAn ES-spec-compliant Set shim/polyfill/replacement that works as far down as ES3
• @formatjs/intl-datetimeformatIntl.DateTimeFormat polyfill

• scroll-into-view-if-needed vs @juggle/resize-observer
• css-vars-ponyfill vs object-fit-images