replacing array

controllers.application\.js

import Controller from '@ember/controller';
import { computed } from '@ember/object';

class Item {  
  constructor(name) {
    this.name = name; 
  }
}

export default Controller.extend({
  name: computed('[email protected]', function () {
    let text = '';
    this.get('arr').forEach(item => {
      text = text + item.name + ';';
    });
    return text;
  }),
  init(...args) {
    this._super(...args);
    this.set('arr', [new Item('zxz')]);
  },

  actions: {
    replaceSecondName() {
			this.set('arr.0.name', 'ppp');
    },
    replaceArr() {
      const newArr = [new Item('baz'), new Item('quux'), new Item('zomg')];
     this.set('arr', newArr);
  	}
  }
});

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<br>

<p>
  names: 
  {{name}}
</p>

<p>
  <button {{action "replaceSecondName"}}>
    Replace second name
  </button>
  
  <button {{action "replaceArr"}}>
    Replace whole array
  </button>
</p>

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.12.2",
    "ember-template-compiler": "3.12.2",
    "ember-testing": "3.12.2"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-data": "3.12.5"
  }
}