webcomponents.js

A suite of polyfills supporting the HTML web components specs:

Custom Elements: allows authors to define their own custom tags (spec).

HTML Imports: a way to include and reuse HTML documents via other HTML documents (spec).

Shadow DOM: provides encapsulation by hiding DOM subtrees under shadow roots (spec).

This also folds in polyfills for MutationObserver and WeakMap.

Builds

webcomponents.js includes all of the polyfills.

webcomponents-lite.js includes all polyfills except for shadow DOM.