ComputedProperty

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  actions: {
    clickHandler() {
      this.get('cards').removeAt(1);
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  cards: Ember.computed('categories', function getCards() {
    return this.get('categories').mapBy('title');
  }),
  
  init() {
  	this.set('categories', Ember.A([
      {
        title: 'card 1',
        subtitle: 'subtitle 1'
      },
      {
        title: 'card 2',
        subtitle: 'subtitle 1'
      },
      {
        title: 'card 3',
        subtitle: 'subtitle 1'
      },      
    ]));
  },
  
  actions: {
    changeCategories() {
      this.set('categories', Ember.A([
        {
          title: 'change categories - card 1',
          subtitle: 'subtitle 1'
        },
        {
          title: 'change categories - card 2',
          subtitle: 'subtitle 2'
        },
        {
          title: 'change categories - card 3',
          subtitle: 'subtitle 3'
        },      
      ]));      
    
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<ul>
  {{#each cards as |cardTitle|}}
    <li>title: {{cardTitle}}</li>
  {{/each}}
</ul>
<button {{action "changeCategories"}}>Change categories</button>

{{my-component cards=cards}}

templates.components.my-component.hbs

{{count}}
<br>
<button {{action "clickHandler"}}>Remove a card</button>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}