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import { LitElement } from 'lit-element';
import { ScopedElementsMixin } from '@open-wc/scoped-elements';
import { MyPanel } from './MyPanel.js';
​
export class MyElement extends ScopedElementsMixin(LitElement) {
  static get scopedElements() {
    return {
      'my-panel': MyPanel,
    };
  }

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import { LitElement, html, css } from 'lit-element';
import { ScopedElementsMixin } from '@open-wc/scoped-elements';
import { FeatureA } from 'feature-a';
import { FeatureB } from 'feature-b';
​
export class PageA extends ScopedElementsMixin(LitElement) {
  static get scopedElements() {
    return {
      'feature-a': FeatureA,
      'feature-b': FeatureB,

daKmoR

import { LitElement } from 'lit-element';
import { ScopedElementsMixin } from '@open-wc/scoped-elements';
import { MyPanel } from './MyPanel.js';
​
export class MyElement extends ScopedElementsMixin(LitElement) {
  static get scopedElements() {
    return {
      'my-panel': MyPanel,
    };
  }

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import { dedupeMixin } from '@open-wc/dedupe-mixin';

export const MyMixin = dedupeMixin(
  superclass =>
    class MyMixin extends superclass {
      // your mixin code goes here
    },
);

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npm i @open-wc/dedupe-mixin

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import { isIE11 } from './helpers.js';

if (isIE11()) {}

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class Page {}
class PageRed extends Page {}
class PageGreen extends Page {}
class PageBlue extends Page {}
class LoggedPagRed extends PageRed {}

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class Page {}
class PageRed extends Page {}
class PageGreen extends Page {}
class PageBlue extends Page {}

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import { dedupeMixin } from '@open-wc/dedupe-mixin';

export const LocalizeMixin = dedupeMixin(
  superclass =>
    class LocalizeMixin extends superclass {
      // this assumes a Mixin for LitElement
      static get properties() {
        return {
          locale: { type: String }
        };

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import { specialAddEventListener } from './helpers.js';

specialAddEventListener(this, 'click', () => console.log('clicked'));