Summary of Polyfills included in @webcomponents/webcomponentsjs

custom-elements.md

custom-elements

Polyfill for Custom Elements

See Patch/Native

html-imports.md

html-imports

Polyfill for HTML Imports

NOTE: Use ECMAScript Modules (ESM) instead!

<link rel="import" href="my-import.html">

shadycss.md

shadycss

Polyfill for Scoped CSS

NOTE: ponyfills (doesn't replicate true Shadow DOM CSS scoping)

• ShadoDOM style encapsulation (ScopingShim)
• Proposed CSS mixin @apply syntax (ApplyShim)
• integrate document-level stylesheets with both of the above (CustomStyleInterface)

shadydom.md

shadydom

Polyfill for Shadow DOM

NOTE: ponyfill for ShadowDOM V1 spec (less correct, but less intrusive and faster than the ShadowDOM polyfill)

• See https://github.com/webcomponents/polyfills/blob/master/packages/shadydom/src/wrapper.js

template.md

template

Polyfill for Template Element

Minimal polyfill for <template>

webcomponentsjs.md

API	Polyfill
Array.from()	webcomponentsjs
CharacterData.after()	webcomponentsjs
CharacterData.before()	webcomponentsjs
CharacterData.remove()	webcomponentsjs
CharacterData.replaceWith()	webcomponentsjs
CustomElementRegistry.define()	custom-elements
CustomElementRegistry.get()	custom-elements
CustomElementRegistry.upgrade()	custom-elements
CustomElementRegistry.whenDefined()	custom-elements
CustomEvent()	webcomponentsjs
Document.append()	custom-elements
Document.append()	webcomponentsjs
Document.createElement()	custom-elements
Document.createElementNS()	custom-elements
Document.importNode()	custom-elements
Document.prepend()	custom-elements
Document.prepend()	webcomponentsjs
Document.replaceChildren()	webcomponentsjs
DocumentFragment.append()	custom-elements
DocumentFragment.append()	webcomponentsjs
DocumentFragment.prepend()	custom-elements
DocumentFragment.prepend()	webcomponentsjs
DocumentFragment.replaceChildren()	webcomponentsjs
Element.after()	custom-elements
Element.after()	webcomponentsjs
Element.append()	custom-elements
Element.append()	webcomponentsjs
Element.attachShadow()	custom-elements
Element.before()	custom-elements
Element.before()	webcomponentsjs
Element.classList	webcomponentsjs
Element.getAttribute()	custom-elements
Element.getAttributeNS()	custom-elements
Element.getAttributeNames()	webcomponentsjs
Element.innerHTML	custom-elements
Element.insertAdjacentElement()	custom-elements
Element.insertAdjacentHTML()	custom-elements
Element.matches()	webcomponentsjs
Element.prepend()	custom-elements
Element.prepend()	webcomponentsjs
Element.remove()	custom-elements
Element.remove()	webcomponentsjs
Element.removeAttribute()	custom-elements
Element.removeAttributeNS()	custom-elements
Element.replaceChildren()	webcomponentsjs
Element.replaceWith()	custom-elements
Element.replaceWith()	webcomponentsjs
Element.setAttribute()	custom-elements
Element.setAttributeNS()	custom-elements
Element.shadowRoot	custom-elements
Event()	webcomponentsjs
EventTarget.addEventListener(type, listener, options)	webcomponentsjs
EventTarget.removeEventListener(type, listener, options)	webcomponentsjs
HTMLElement()	custom-elements
HTMLElement.classList	webcomponentsjs
HTMLElement.innerHTML	custom-elements
HTMLElement.insertAdjacentElement()	custom-elements
HTMLElement.insertAdjacentHTML()	custom-elements
HTMLTemplateElement	template
Map[Symbol.iterator]	webcomponentsjs
MouseEvent()	webcomponentsjs
Node.appendChild()	custom-elements
Node.baseURI	webcomponentsjs
Node.cloneNode()	custom-elements
Node.getRootNode()	shadydom
Node.insertBefore()	custom-elements
Node.isConnected	shadydom
Node.removeChild()	custom-elements
Node.replaceChild()	custom-elements
Node.textContent	custom-elements
Object.assign()	webcomponentsjs
Object.getOwnPropertySymbols()	webcomponentsjs
Object.keys()	webcomponentsjs
Object.toString()	webcomponentsjs
SVGElement.classList	webcomponentsjs
Set[Symbol.iterator]	webcomponentsjs
String[Symbol.iterator]	webcomponentsjs
Symbol	webcomponentsjs
window.Promise	webcomponentsjs
window.customElements	custom-elements

NOTE

• Element.closest() - NOT polyfilled!