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import Component from '@glimmer/component';

// This component renders its contents in a shadow root:
//
// <ShadowRoot>stuff</ShadowRoot>
//
// Critically, it renders in a single render pass. The more natural
// modifier-based solutions do not.
//
// The "trick" we're relying on here is the little-known feature that helpers

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Webpack 5 Node Polyfills Upgrade Cheatsheet

Webpack 4 automatically polyfilled many Node APIs in the browser. This was not a great system, because it could lead to surprisingly giant libraries getting pulled into your app by accident, and it gave you no control over the exact versions of the polyfills you were using.

So Webpack 5 removed this functionality. That means you need to make changes if you were relying on those polyfills. This is a quick reference for how to replace the most common patterns.

List of polyfill packages that were used in webpack 4

For each automatically-polyfilled node package name on the left, this shows the name of the NPM package that was used to polyfill it on the right. Under webpack 5 you can manually install these packages and use them via resolve.fallback.

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import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

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import Ember from 'ember';

export default Ember.Component.extend({
  rows: Ember.computed('names', function() {
    let names = this.get('names');
    let columns = Math.floor($(window).width() / 100);
    let itemsPerColumn = Math.ceil(names.length / columns);
    
    let rows = [];
    for (let rowNumber = 0; rowNumber < itemsPerColumn; rowNumber++) {

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import Ember from 'ember';

export default Ember.Controller.extend({
  nothing() {}
});

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let writeFile = require('broccoli-file-creator');


treeForPublic: function() {
  const publicTree = this._super.treeForPublic.apply(this, arguments);
  const trees = [];
  if (publicTree) {
    trees.push(publicTree);
  }
  trees.push(writeFile('the-settings-file.json', this.whateverTheSettingsAre());

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How to use positionalParams in Angle Bracket invocation

A component with positionalParams always also has named versions of its parameters. For example, the liquid-if component from liquid-fire has this in its Javascript file:

positionalParams: ['predicate']

So these are equivalent:

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import Ember from 'ember';

const { Component } = Ember;

export default class EachChunk extends Component {};

EachChunk.tagName = '';

EachChunk.reopenClass({
  positionalParams: ['items', 'chunkSize']

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import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  valueList: Ember.A([1, 2, 3, 4]),
  updateVal(index, newValue) {
    this.valueList.replace(index, 1, newValue);
  }
});

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import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  valueList: [1, 2, 3, 4],
  updateVal(index, newValue) {
    this.set('valueList', this.valueList.map((oldValue, i) => index === i ? newValue : oldValue));
  }
});