lifecycle test

components.my-foo.js

import Ember from 'ember';

export default Ember.Component.extend({
  bar: null,
  valAtInit: null,
  valAtDRA: null,
  
  init() {
    this._super(...arguments);
    console.log('init', this.bar);
    this.set('valAtInit', this.bar);
  },
  
  didReceiveAttrs() {
    this._super(...arguments);
    console.log('didReceiveAttrs', this.bar);
    this.set('valAtDRA', this.bar);
  }
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-foo bar="baz"}}
<br>
<br>

templates.components.my-foo.hbs

<div>
  Passed Value: {{bar}}
</div>
<div>
  Value at Init: {{valAtInit}}
</div>
<div>
  Val at didReceivAttrs: {{valAtDRA}}
</div>

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"
  }
}