Support for built-in elements

A new version 2.0.1-beta.217 of the patterns-library has just been released 🎉 including breaking changes 💣 :

• Replaced existing polyfill by a battle-tested, feature-complete polyfill by WebReflection, namely document-register-element and @ungap/custom-elements-builtin
• All components can’t use the constructor() any more and should use init(), which is called with the proper contexts - see caveats V1 https://github.com/WebReflection/document-register-element#v1-caveat

Migration

1. Replace your existing polyfill:
   • remove old and broken polyfill import '@webcomponents/webcomponentsjs/bundles/webcomponents-ce';
   • and use shiny new working polyfill:

     // better to load this only if it's needed
     import 'document-register-element/'; // ES2015
     // load this for browsers which support customElements without builtin (webkit)
     import '@ungap/custom-elements-builtin';

2. All constructors need to be replaced by init, like so:
   • construcor(...) { super(...); } -> init(...) {} super.init(...); }